Growing source of meat and milk (7)

I believe the answer is:

coconut

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'growing source' is the definition.
'coconut' can be an answer for 'source' (I have seen 'source of oil' mean 'coconut' so perhaps 'source' could also mean 'coconut'). I'm not certain of the 'growing' bit.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for coconut that I've seen before include "cut from the palm?" , "that's hairy and tough!" , "source of oil" , "Hairy, milk-containing fruit of the palm" , "Shy target?" .)

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

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