Crazy, sacrificing last of rhubarb for pineapple! (6)

I believe the answer is:

ananas

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'for pineapple' is the definition.
(synonyms)

I don't understand the rest of the clue.

(Other definitions for ananas that I've seen before include "Black top on this fruit" , "F" , "Pineapple" , "piece of fruit" , "Sort of fruit" .)

I've seen this clue in The Times.

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