In contact with, not friends with (7)

I believe the answer is:

against

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'in contact with' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for against that I've seen before include "Opposite to" , "V" , "Versus - in contact with" , "Not supporting" , "In opposition to" .)

I've seen this clue in The Times.

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