Replace a button (3)
I believe the answer is:
sew
'replace a button' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sew that I've seen before include "Do some needlework" , "Fasten with stitches" , "Stitch with needle and thread" , "Tack" , "Make stitches" .)