Of the moon (5)
I believe the answer is:
lunar
'of the moon' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lunar that I've seen before include "Moon's" , "Belonging to the moon" , "Pertaining to the moon" , "that could describe landscape with more than one mare" , "of a circling body" .)