Riddles concerning broken fists (5)
I believe the answer is:
sifts
'riddles' is the definition.
(I've seen this before)
'broken fists' is the wordplay.
'broken' indicates anagramming the letters.
'fists' anagrammed gives 'SIFTS'.
'concerning' acts as a link.
(Other definitions for sifts that I've seen before include "Passes through a sieve" , "Strains, sieves" , "Riddles" .)