Instant credit (4)

I believe the answer is:

tick

I believe this clue is a double definition.

'instant' is the first definition.
(I've seen this before)

'credit' is the second definition.
(I've seen this in other clues)

(Other definitions for tick that I've seen before include "Beat" , "Sound of an old watch" , "sign of approval from teacher" , "Little bloodsucker" , "Blood-sucking arachnid" .)

I've seen this clue in The Independent.

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