Find boxer I’d upset (3,2)
I believe the answer is:
dig up
'find' is the definition.
(dig up can mean to discover)
'boxer i'd upset' is the wordplay.
'boxer' becomes 'pug' (short for pugilist - term for boxer).
'upset' says the letters should be written backwards.
'pug'+'id'='pugid'
'pugid' reversed gives 'DIG UP'.
(Other definitions for dig up that I've seen before include "Unearth" , "Excavate - discover" , "Exhume" , "Uncover (something hidden)" , "Find" .)