Attempt to influence; fix (6)

I believe the answer is:

tamper

(Other definitions for tamper that I've seen before include "Interfere or alter without authority" , "'Alter or falsify, documents perhaps (6)'" , "Machine for compacting earth; interfere (with)" , "Interfere harmfully" , "Meddle or interfere with" .)

I've seen this clue in The Guardian.

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