Repair ripped denim I discarded (4)
I believe the answer is:
mend
'repair' is the definition.
(I know that repair can be written as mend)
'ripped denim i discarded' is the wordplay.
'ripped' is an anagram indicator (letters ripped or torn up).
'discarded' indicates named letters should be taken away.
'denim' with 'i' removed is 'denm'.
'denm' with letters rearranged gives 'MEND'.
(Other definitions for mend that I've seen before include "Make improvements" , "Heal" , "Return to health; repair" , "'Restore, fix (4)'" , "Fix, repair" .)