Crazy Conservative entertained by gents? (4)
I believe the answer is:
loco
'crazy' is the definition.
(loco can informally mean mad)
'conservative entertained by gents?' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'entertained by' indicates putting letters inside (inserted letters are hosted or entertained).
'gents?' becomes 'loo' (I've seen this in other clues).
'c' put within 'loo' is 'LOCO'.
(Other definitions for loco that I've seen before include "with a screw loose?" , "Barmy (Spanish) - engine (abbr)" , "Railway engine - mad!" , "Round the bend" , "Mad - train" .)