Clear; shining (5)
I believe the answer is:
lucid
I believe this is a double definition.
'clear' is the first definition.
(similar in meaning)
'shining' is the second definition.
(I've seen this before)
(Other definitions for lucid that I've seen before include "Rational, clear" , "completely clear" , "Compos mentis" , "Quite clear" , "Transparently clear" .)