Be the perfect match, if not all the time? (8)
I believe the answer is:
fitfully
'not all the time?' is the definition.
I can't judge whether this defines the answer.
'be the perfect match' is the wordplay.
'be' becomes 'fit' (fitting is a kind of being).
'the perfect match' becomes 'fully' (I am not sure about this - if you are sure you should believe this answer much more).
'fit'+'fully'='FITFULLY'
'if' is the link.
Can you help me to learn more?
(Other definitions for fitfully that I've seen before include "Spasmodically" , "Only at times" , "not consistently" , "Intermittently" , "occurring in bouts?" .)
