Chaps getting start of drugs fix (4)
I believe the answer is:
mend
'fix' is the definition.
(I know that fix can be written as mend)
'chaps getting start of drugs' is the wordplay.
'chaps' becomes 'men' (chap means a man).
'getting' means one lot of letters go next to another.
'start of' suggests taking the first letters.
The first letter of 'drugs' is 'd'.
'men'+'d'='MEND'
(Other definitions for mend that I've seen before include "'Restore, fix (4)'" , "Fix, repair" , "Make improvements" , "Put right" , "Heal" .)