Small problem or difficulty (4)
I believe the answer is:
snag
I believe this is a double definition.
'small problem' is the first definition.
(I've seen this in another clue)
'difficulty' is the second definition.
(snag is a kind of difficulty)
(Other definitions for snag that I've seen before include "Hidden obstacle or catch" , "Hidden obstacle or drawback" , "Unexpected drawback" , "Hidden drawback; tear" , "Hitch, unexpected problem" .)