Promised disheartened pal, getting nicked (7)
I believe the answer is:
pledged
'promised' is the definition.
(pledging is a kind of promising)
'disheartened pal getting nicked' is the wordplay.
'disheartened' says to hollow out the word (remove centre letters).
'getting' is a charade indicator (letters next to each other).
'nicked' becomes 'edged' (I've seen this before).
'pal' with its centre taken out is 'pl'.
'pl'+'edged'='PLEDGED'
(Other definitions for pledged that I've seen before include "getting engaged" , "Promised or pawned" , "Promised solemnly and formally" , "Made promise" , "Bound by oath" .)