Put out, I carp (3)
I believe the answer is:
koi
'carp' is the definition.
(I've seen this before)
'put out i' is the wordplay.
'put out' becomes 'ko' (abbreviation for knock out**).
'ko'+'i'='KOI'
(Other definitions for koi that I've seen before include "Japanese type of carp" , "Sort of carp" , "Ornamental carp variety" , "Kind of decorative carp" , "sort of fish" .)