Star lass leaving gambling city (4)
I believe the answer is:
vega
'star' is the definition.
(Vega is an example)
'lass leaving gambling city' is the wordplay.
'leaving' suggests deleting specific letters.
'gambling city' becomes 'lasvegas' (I've seen this before).
'lasvegas' with 'lass' taken out is 'VEGA'.
(Other definitions for vega that I've seen before include "Bright star of constellation Lyra" , "heavenly body" , "Fifth brightest star" , "Brightest star of constellation Lyra" , "First magnitude star" .)