Left a new bird some light (7)
I believe the answer is:
lantern
'some light' is the definition.
(lantern is a kind of light)
'left a new bird' is the wordplay.
'left' becomes 'l' (common abbreviation).
'a new' becomes 'an' (I've seen this in other clues).
'bird' becomes 'tern' (tern is a kind of bird**).
'l'+'an'+'tern'='LANTERN'
(Other definitions for lantern that I've seen before include "Enclosed light" , "Lamp with protective transparent casing" , "Light held by 26/27 Across" , "Cased lamp" , "Top of lighthouse" .)