A fit, more or less (5)
I believe the answer is:
about
'more or less' is the definition.
('about' can be a synonym of 'more or less')
'a fit' is the wordplay.
'fit' becomes 'bout' (I've seen this in other clues).
'a'+'bout'='ABOUT'
(Other definitions for about that I've seen before include "Approximately, or in vicinity" , "Nearly" , "In conection with, all around" , "On the subject of, approximately" , "On the topic of" .)