Drink less gin to inspire sheer love (7)
I believe the answer is:
nothing
'drink less gin' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'to inspire sheer love' is the wordplay.
'to inspire' is an insertion indicator (inspire can mean to breathe in).
'sheer' becomes 'thin' ('thin' can be similar in meaning to 'sheer').
'love' becomes 'nog' (I can't explain this - if you can you should believe this answer much more).
'thin' inserted within 'nog' is 'NOTHING'.
(Other definitions for nothing that I've seen before include "trivial event" , "One of those sweet sayings" , "Zilch, nada" , "signifying love" , "unimportant or > unintelligible" .)