Short time ahead of it, a new moon (5)
I believe the answer is:
titan
'moon' is the definition.
(moon of Saturn)
'short time ahead of it a new' is the wordplay.
'short time' becomes 't' (abbreviation for time).
'ahead of' says to put letters next to each other (I've seen this in other clues).
'a new' becomes 'an' (I've seen this in other clues).
't'+'it'+'an'='TITAN'
(Other definitions for titan that I've seen before include "Huge character" , "One of the mythological Greek giants who ruled the world" , "Mythological giant" , "Goddess" , "Rhea, perhaps" .)