Pugilist's rib sure to be injured (7)
I believe the answer is:
bruiser
'pugilist's' is the definition.
(thesaurus)
'rib sure to be injured' is the wordplay.
'to be injured' indicates anagramming the letters.
'rib'+'sure'='ribsure'
'ribsure' is an anagram of 'BRUISER'.
(Other definitions for bruiser that I've seen before include "Tough, aggressive person" , "tough guy" , "Large tough man, inflicts flesh discolourations" , "Strong aggressive person" , "Fighter - rues rib (anag)" .)