Initial tree on street (5)

I believe the answer is:

first

'initial' is the definition.
('first' can be similar in meaning to 'initial')

'tree on street' is the wordplay.
'tree' becomes 'fir' (fir is a kind of tree).
'on street' becomes 'st' (I've seen this in other clues).
'fir'+'st'='FIRST'

(Other definitions for first that I've seen before include "second to none" , "in dominant position" , "Foremost" , "Prime" , "Cardinal" .)

I've seen this clue in The Guardian.

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