Signed up, having listened for a change (8)
I believe the answer is:
enlisted
'signed up' is the definition.
(enlisting is a kind of signing up)
'listened for a change' is the wordplay.
'for a change' indicates anagramming the letters.
'listened' is an anagram of 'ENLISTED'.
'having' is the link.
(Other definitions for enlisted that I've seen before include "Lower ranks in US army" , "Joined forces" , "Enrolled" , "Listened (anag.)" , "Joined the military" .)