Trick girl into scattering a lot of stars (13)
I believe the answer is:
constellation
'a lot of stars' is the definition.
(a constellation is a group of stars)
'trick girl into scattering' is the wordplay.
'trick' becomes 'con' (a con is a fraud or trick).
'girl' becomes 'stella' ().
'scattering' indicates an anagram.
'into' is an anagram of 'tion'.
'con'+'stella'+'tion'='CONSTELLATION'
(Other definitions for constellation that I've seen before include "Client to salon (anag.)" , "Twins, perhaps" , "Twenty-five across for instance" , "E.g Orion, Andromeda" , "Star group" .)