Q:

Question on leading

In bridge, what is the priority in leading when partner bid spades, and contract is clubs, and I have ace and queen of spades. Does the rule "do not underlead an ace" here override the rule "lead with the suit that your partner has bid"?

A:

Consider a few different scenarios:

Partner overcalled 1S and contract is 3NT: Lead the spade A followed by the spade Q to unblock the suit. Presumably partner has 6 to the JT, and declarer just might be adventuring on a singleton K.
Partner opened 1S and the contract is 3NT: Same reasoning, same lead.
You opened and partner made a 1-over-1 bid of 1S, contract is 3NT: Find another suit to lead, and hope partner can get in to lead through declarer's spade K. Partner's spade bid was length-showing, showing 4, and nothing more. You have the bulk of the partnership assets, and the best chance of establishing (and cashing) length tricks to set the contract with. 
Partnered opened a weak 2 Spades and the contract is 3NT: Treat this like case (1).
The contract is in a suit (below slam)and the opponents bid it to make: Lead something else unless you really trust partner to be holding the spade K. Partner bid, so has a realistic chance to get in and lead spades. Lead a card that invites partner to switch rather than one that asks partner to continue.
The contract is in a suit (below slam) and the opponents bid it as a sacrifice: Probably best to lead the spade A.
The contract is a suit slam: Usually best to lead spade A.

These are general guidelines, and not "rules". There are other factors that will affect your choice of lead:

Consider the bidding as well. Did the opponents reach 3NT tentatively or aggressively? In the former case an aggressive lead of the spade A is more appealing than in the latter.
Are you playing Matchpoints, IMPS or Rubber? Conceding an overtrick in Matchpoints is as costly as forgetting to set opponents game in IMPS or Rubber, so be wary of leading spades against confident opponents. In IMPS or Rubber lead the spade A because a lost overtrick means nothing compared to a best chance of a set.
Is your partner one who likes to psyche frequently? If so, find another suit to lead than spades; You know it is likely that partner psyched, but the opponents don't now that yet. This is fair dinkum because the bidding and visible cards drew you to this conclusion, not any tells on his part.
Is your partner one of those who insists that his suit be lead?  If yes, and this partner is one you wish to continue playing with, lead the spade A (unless something else is overwhelmingly better). One bad result is nothing compared to playing with a partner you enjoy and respect.

You will notice that the latter guidelines for the most part contradict the former scenario suggestions; this is deliberate. Leading well is part science, part art, and part black magic.

