Champion boxer perhaps? (3,3)
I believe the answer is:
top dog
'champion' is the definition.
(I've seen this in another clue)
'boxer perhaps?' is the wordplay.
I cannot quite understand how this works, but
'boxer' could be 'dog' (I've seen this in other clues) and 'dog' is present in the answer.
The remaining letters 'top' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for top dog that I've seen before include "Supremo or master canine" , "Dominant individual" , "First" , "Member of learned society" , "Successful person - Crufts' winner?" .)