Chaps with a lot to repair (4)
I believe the answer is:
mend
'to repair' is the definition.
('mend' can be a synonym of 'repair')
'chaps with a lot' is the wordplay.
'chaps' becomes 'men' (chap can mean a man).
'with' says to put letters next to each other.
'a lot' becomes 'd'.
'men'+'d'='MEND'
(Other definitions for mend that I've seen before include "Make improvements" , "'Restore, fix (4)'" , "Return to health; repair" , "Fix, repair" , "Put right" .)