Plenty of beer drunk by backbencher? On the contrary (5)
I believe the answer is:
ample
'plenty of' is the definition.
(I've seen this in another clue)
'beer drunk by backbencher? on the contrary' is the wordplay.
I cannot really see how this works, but
'backbencher?' could be 'mp' (backbencher is a type of Member of Parliament) and 'mp' is located in the answer.
'beer' could be 'ale' (type of beer) and 'ale' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for ample that I've seen before include "Generous" , "Plentiful, quite enough" , "Plenty, more than enough" , "Big" , "Copious - abundant" .)