Power boxing oddly wielded for boxer (12)
I believe the answer is:
middleweight
'boxer' is the definition.
(middleweight is a kind of boxer)
'power boxing oddly wielded' is the wordplay.
'power' becomes 'might' ('might' can be a synonym of 'power'**).
'boxing' indicates putting letters inside ('box' can mean contain, as in to put in a box).
'oddly' indicates anagramming the letters.
'wielded' is an anagram of 'iddlewe'.
'might' enclosing 'iddlewe' is 'MIDDLEWEIGHT'.
'for' is the link.
(Other definitions for middleweight that I've seen before include "Boxing category" , "Boxer" .)