Firm hug can end upset (9)
I believe the answer is:
Here is my best explanation:
'firm' is the definition.
'hug can end upset' is the wordplay.
'upset' indicates anagramming the letters.
'hugcanend' with letters rearranged gives 'UNCHANGED'.
(Other definitions for unchanged that I've seen before include "The same", "Unaltered", "Not altered" and "Remaining in an original state".)