Unifying agent making biscuit (9)

I believe the answer is:

garibaldi

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

I can't explain the remainder of the clue.

(Other definitions for garibaldi that I've seen before include "blouse, loose one" , "Italian nationalist; biscuit" , "leader of nationalists" , "military commander" , "Currant biscuit - Italian patriot" .)

I've seen this clue in The Telegraph.

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