Vent, perhaps, without revolving glass door (6,6)

I believe the answer is:

french window

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'glass door' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for french window that I've seen before include "Glazed way out to garden/balcony" , "Glazed door" , "Glass door" , "Patio door?" .)

I've seen this clue in The Times.

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