Hero who started bowling with a broken arm! (5)
I believe the answer is:
rambo
'hero' is the definition.
(I have seen 'Brainless hero' mean 'rambo' so perhaps 'hero' could also mean 'rambo')
'started bowling with a broken arm' is the wordplay.
'started bowling' becomes 'bo' (I can't explain this - if you can you should believe this answer much more).
'with' says to put letters next to each other.
'a broken' is an anagram indicator.
'arm' anagrammed gives 'ram'.
'bo' put after 'ram' is 'RAMBO'.
'who' acts as a link.
Can you help me to learn more?
(Other definitions for rambo that I've seen before include "Tough man (films)" , "Character relying on brute force" , "Tough film hero" , "Senseless violent person" , "Stallone tough guy" .)