Clarify; resolve (5,2)
I believe the answer is:
clear up
I believe this clue is a double definition.
'clarify' is the first definition.
(synonyms)
'resolve' is the second definition.
(I've seen this in another clue)
(Other definitions for clear up that I've seen before include "Get better" , "Straighten out" , "Resolve" , "Sort out" , "iron out" .)