Dog I record as boxer (8)
I believe the answer is:
pugilist
'boxer' is the definition.
('pugilist' can be a synonym of 'boxer')
'dog i record' is the wordplay.
'dog' becomes 'pug' (pug is a kind of dog).
'record' becomes 'list' (I've seen this before).
'pug'+'i'+'list'='PUGILIST'
'as' acts as a link.
(Other definitions for pugilist that I've seen before include "Fist fighter" , "Prize fighter" , "A professional boxer" .)