Smashed bottle he blew -- that's unfair (5,3,4)
I believe the answer is:
below the belt
'unfair' is the definition.
(I've seen this before)
'smashed bottle he blew' is the wordplay.
'smashed' indicates anagramming the letters.
'bottle'+'he'+'blew'='bottleheblew'
'bottleheblew' is an anagram of 'BELOW THE BELT'.
'that's' acts as a link.
(Other definitions for below the belt that I've seen before include "Hang scabbard here" , "fly is here" , "Not fair" , "Unfair, disregarding the rules" , "Unfair, cheating" .)