Mighty clear (6)
I believe the answer is:
strong
I believe this is a double definition.
'mighty' is the first definition.
(thesaurus)
'clear' is the second definition.
(thesaurus)
(Other definitions for strong that I've seen before include "Convincing" , "Powerful; full-flavoured" , "Great in power" , "Mighty, powerful" , "firm" .)