Edited clue — firm but forgiving (8)
I believe the answer is:
'forgiving' is the definition.
(similar in meaning)
'edited clue firm' is the wordplay.
'edited' indicates anagramming the letters.
'cluefirm' is an anagram of 'MERCIFUL'.
'but' is the link.
(Other definitions for merciful that I've seen before include "Kind" , "Clement - forbearing" , "Humane" , "Compassionate, forgiving" , "Being disposed to show clemency" .)