Left object illuminated (3)
I believe the answer is:
lit
'illuminated' is the definition.
(synonyms)
'left object' is the wordplay.
'left' becomes 'l' (common abbreviation).
'object' becomes 'it' (pronoun for an inanimate object).
'l'+'it'='LIT'
(Other definitions for lit that I've seen before include "fine writing in condensed form" , "Ignited, say cigarette" , "Fired" , "Set fire to" , "books etc?" .)