New moon, sure to be huge (8)
I believe the answer is:
enormous
'be huge' is the definition.
(synonyms)
'new moon sure' is the wordplay.
'new' indicates an anagram.
'moon'+'sure'='moonsure'
'moonsure' with letters rearranged gives 'ENORMOUS'.
'to' acts as a link.
(Other definitions for enormous that I've seen before include "Colossal, huge" , "Immense" , "Vast" , "Gross" , "Unusually large - jumbo" .)