Left the thing looking brighter! (3)

I believe the answer is:

lit

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'looking brighter' is the definition.
I can't judge whether this definition defines the answer.

'left the thing' is the wordplay.
'left' becomes 'l' (common abbreviation).
'the thing' becomes 'it'.
'l'+'it'='LIT'

Can you help me to learn more?

(Other definitions for lit that I've seen before include "Set alight" , "fine writing in condensed form" , "Set fire to" , "Fired" , "Enlightened" .)

I've seen this clue in the Evening Standard.

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