Top bid — never the bottom (2-5)
I believe the answer is:
no-trump
'top bid' is the definition.
'no trump' can be an answer for 'bid' (I've seen this before). I'm not certain of the 'top' bit.
'never the bottom' is the wordplay.
'never' becomes 'not' (I've seen this in other clues).
'the bottom' becomes 'rump' (rump can informally mean someone's bottom).
'not'+'rump'='NO-TRUMP'
Can you help me to learn more?
(Other definitions for no-trump that I've seen before include "possible contract" , "that many left-wing Americans desire?" , "Bid in contract bridge" , "Bid type that's top" , "Highest bid in bridge" .)