Repair-guys don't start (4)
I believe the answer is:
mend
'repair' is the definition.
(I know that repair can be written as mend)
'guys don't start' is the wordplay.
'guys' becomes 'men' (guy can mean a man).
'start' suggests taking the first letters.
The initial letter of 'dont' is 'd'.
'men'+'d'='MEND'
(Other definitions for mend that I've seen before include "Fix, repair" , "Put right" , "'Restore, fix (4)'" , "Heal" , "Return to health; repair" .)