He's crying, having registered as a fighter (7)
I believe the answer is:
brawler
'a fighter' is the definition.
(I know that brawler is a type of fighter)
'he's crying having registered' is the wordplay.
I cannot quite see how this works, but
'registered' could be 'r' (abbreviation, as in registered trademark) and 'r' is present in the answer.
The remaining letters 'bawler' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'as' is the link.
Can you help me to learn more?
(Other definitions for brawler that I've seen before include "Yobbo" , "Street fighter" .)