How to address "positively" an unemployment gap for a postdoc application in a CV I’m planning to apply for a postdoc in Europe but in the eligibility conditions section for this position, it is written that the PhD shouldn’t be obtained more than 3 years ago unless it is a case of serious illness or parental leave.

I obtained my PhD 4 years ago and I had 2 years of unemployment gap. I'm from a developing country and the job market is simply very tough here. 

Is there a way to clarify this in a positive way in my CV or cover letter and to apply for the position?
The job announcement contains a contact person - a professor or the head of a department, often. Contact them, state your situation, and ask if it is possible to get the job regardless. If you know someone from the faculty or the country, you might also ask them informally, first.

If you, for example, had family reasons to not leave a particular city, where you could not get a position, that might qualify as a sufficient reason. State any relevant reason, but do it in short manner. Get to the point.

Also, in some countries it is possible to hire you under a different title (researcher vs. postdoc, for example) in spite of the work history. It might be that the condition in the announcement is not binding for some other reason.

You will not know of such factors without asking, so just ask.

For example

Dear professor,

I wish to apply to the position [link to the job announcement and name of the position], which says that my PhD must be no more than three years old [or whatever it states, precisely]. My PhD is four years old, for [reasons]. Is it possible to get the job?