A large blue permit (5)

I believe the answer is:

allow

'permit' is the definition.
(I know that permit can be written as allow)

'a large blue' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'blue' becomes 'low' (I've seen this in another clue).
'a'+'l'+'low'='ALLOW'

(Other definitions for allow that I've seen before include "Give permission to" , "Permit, let happen" , "Acknowledge - concede" , "OK" , "Permit or agree" .)

I've seen this clue in The Independent.

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