Prizefighter is sure rib is cracked (7)
I believe the answer is:
bruiser
'prizefighter' is the definition.
(I've seen this before)
'sure rib is cracked' is the wordplay.
'is cracked' indicates an anagram.
'sure'+'rib'='surerib'
'surerib' is an anagram of 'BRUISER'.
'is' acts as a link.
(Other definitions for bruiser that I've seen before include "Big aggressive man" , "tough guy" , "Informally, a large tough person, maybe a boxer" , "Strong aggressive person" , "Prizefighter" .)