A big fiddle leaving little room for love (5)
I believe the answer is:
cello
'a big fiddle' is the definition.
(large fiddle-like instrument)
'little room for love' is the wordplay.
'little room' becomes 'cell' (I've seen this before).
'for' is a charade indicator (letters next to each other).
'love' becomes 'o' (love means zero in tennis).
'cell'+'o'='CELLO'
'leaving' acts as a link.
(Other definitions for cello that I've seen before include "Casals' instrument" , "Played by Rostropovich" , "Orchestral instrument played between the legs" , "It's bigger than a viola, but smaller than a double bass" , "music produced by this?" .)