It may be greased to ensure things go smoothly (4)

I believe the answer is:

palm

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'it may be greased' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for palm that I've seen before include "Symbol of victory" , "Date-tree" , ""trophy"" , "Evergreen tree and part of the hand" , "Tree - front of the hand" .)

I've seen this clue in The Irish Times.

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