Female replaces male in gloomy bar (6)

I believe the answer is:

forbid

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'bar' is the definition.
(I know that bar is a more specific form of the action forbid)

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for forbid that I've seen before include "Ban" , "Refuse permission, do not allow" , "Outlaw" , "Prohibit, veto" , "Refuse permission, order not to" .)

I've seen this clue in The Sun.

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