King of the sun and the new moon (7)
I believe the answer is:
solomon
'king' is the definition.
(I've seen this before)
'the sun and the new moon' is the wordplay.
'the sun' becomes 'sol' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'the new' indicates anagramming the letters.
'moon' is an anagram of 'omon'.
'sol'+'omon'='SOLOMON'
'of' is the link.
(Other definitions for solomon that I've seen before include "Wise old king of Israel" , "King of Israel with great wisdom" , "King known for wisdom" , "King of Egypt famous for wisdom and magnificence" , "King of Israel noted for his wisdom" .)