Barista's warning police still? (7)

I believe the answer is:

mugshot

'police still?' is the definition.
(photograph or still taken by the police)

I don't understand the remainder of the clue.

(Other definitions for mugshot that I've seen before include "Police photo (colloq.)" , "Passport photograph?" , "Still capturing the culprit" , "ID photograph (colloq.)" , "Police ID photograph" .)

I've seen this clue in The Guardian.

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