Sorts of riddles? (5)
I believe the answer is:
sifts
I believe this is a double definition.
'sorts' is the first definition.
(I've seen this in another clue)
'riddles?' is the second definition.
(riddling is a kind of sifting)
'of' acts as a link.
(Other definitions for sifts that I've seen before include "Passes through a sieve" , "Strains, sieves" , "Riddles" .)