Tenure-track offer with other applications in progress I am an academic in computer science in Europe, just completed my Ph.D. and applied for tenure-track positions in Europe. I received a very early offer in the UK more than a month ago and the negotiation stretched until now. Given the overal small startup packages in the UK, I managed to negotiate for a decent startup budget. However, as the department has no presence nor material for the research I am doing, the deal is more average/minimal. Apart from the details in the offer, the thing that is holding me back is that my partner also has a good career here but in the UK, she would have a very hard time and probably have to go back to university to make her degree compatible. We discussed all of this and I would take the offer if all other applications do not work out. Now the university really wants me to make a decision this week.

I have a tenure-track application running at my home university where I did my studies, grew up, and I am still living. The place is quite decent and despite the down-sides of staying at the same place, I would be very happy with the position as I was able to do good work here in the past, and my partner would be able to continue her career as well. I have a good chance of receiving an offer here but the interview and results will be out in 3-4 weeks. I contacted the university but they cannot speed-up the process. The other thing is that the position at the university here is quite exceptional in that a similar position will not be available anytime soon. As there not many/no universities that have a presence in my field nearby, this is the one opportunity for my partner and I to live in our hometown. 

So I need to make a decision this week on an offer in the UK which I would totally take if the outcome on the other application would be negative. The application at my home university, which would be my preferred choice, will still take 3 weeks. If I say NO to the offer in the UK, I could end up with no position. The safest thing would be to say YES this week. But potentially canceling the offer in 3 weeks, when the results at my home university are out, is probably not very ethical? 

Just for completeness, I have another tenure-track application at a university nearby, this could be a backup, but is very uncertain as it is not specifically focusing on my area of research.

I would welcome any advise or hear about similar experiences.
I think what you are asking is if there is an ethical way to accept a position and then bail if you get a better position. Ethics are often very personal, but I think most people would conclude that this is unethical. That said, potentially the more important question, is can you get away with the behavior. From a legal standpoint, there is likely very little that can be done to punish you.

From a career standpoint accepting an offer and then turning it down tends to be a recipe for creating academic enemies. In your case, however, I think you can get away with it because of the Brexit and the fact you have a partner. If in the next month you get a better offer, you can tell the UK university that your partner has had a change of heart. Yes, I am advocating blaming it all on your partner to keep you from making enemies. Explain that your partner is concerned about moving to the UK because of Brexit and their treatment of foreigners. Yes, I am advocating telling a straight up lie. UK academics are generally up in arms about the Brexit. Having a change of heart because of the Brexit will be totally believable to them.