Fruitful source of information (9)

I believe the answer is:

grapevine

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'source of information' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for grapevine that I've seen before include "Unofficial oral relaying of information" , "fruit producer" , "Informal source of information" , "where fruit is grown" , "(Informal) means of spreading information?" .)

I've seen this clue in The Globe and Mail.

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