Warning about strain by doctor: one that has a lot in it? (7,6)

I believe the answer is:

fortune cookie

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But I can't explain it at all! Could you help me understand?

(Other definitions for fortune cookie that I've seen before include "Biscuit containing a message" , "Small biscuit containing a prediction" , "Pastry containing maxim" , "Chinese restaurant speciality" , "Biscuit containing a prophecy" .)

I've seen this clue in The Times.

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