Make alterations to tremendous trousers (5)
I believe the answer is:
emend
'make alterations' is the definition.
(I've seen this before)
'tremendous trousers' is the wordplay.
'trousers' says the answer is hidden in the clue (trouser can mean to steal or take).
'EMEND' can be found hidden inside 'tremendous'.
'to' is the link.
(Other definitions for emend that I've seen before include "Alter to improve (text)" , "Polish" , "Edit; make alterations to a draft" , "Modify" , "Improve (writing)" .)