Love quest oversight (8)
I believe the answer is:
omission
'oversight' is the definition.
(omission is a kind of oversight)
'love quest' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'quest' becomes 'mission'.
'o'+'mission'='OMISSION'
(Other definitions for omission that I've seen before include "cut?" , "It may create space" , "Something lacking" , "Something left out or neglected" , "Negligence" .)