Notice the chaps going in to change (5)
I believe the answer is:
amend
'change' is the definition.
(amending is a kind of changing)
'notice the chaps going in' is the wordplay.
'notice' becomes 'ad' (short for advert).
'the chaps' becomes 'men' (chap means a man).
'going in' indicates putting letters inside.
'ad' going around 'men' is 'AMEND'.
'to' acts as a link.
(Other definitions for amend that I've seen before include "Change for the better" , "Correct error, make minor alteration as to writing" , "Alter in detail" , "Correct (one's ways)" , "make an improvement" .)