Make clear; explain (7)
I believe the answer is:
clarify
I believe this clue is a double definition.
'make clear' is the first definition.
(synonyms)
'explain' is the second definition.
(I know that clarify is a type of explain)
(Other definitions for clarify that I've seen before include "Elucidate" , "Make easily understood" , "Make more comprehensible" , "Explain" , "Make clear" .)