Bar staff finally on site dressed as pirates (12)

I believe the answer is:

counterfeits

'pirates' is the definition.

'bar staff finally on site dressed' is the wordplay.
'bar' becomes 'counter' (I've seen this before).
'finally' suggests the final letters.
'on' is an insertion indicator.
'dressed' indicates anagramming the letters ('dress' can mean 'prepare').
The final letter of 'staff' is 'f'.
'site' with letters rearranged gives 'eits'.
'f' placed into 'eits' is 'feits'.
'counter'+'feits'='COUNTERFEITS'

'as' is the link.

I've seen this clue in The Guardian.

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