Study of life in simple form (7,7)

I believe the answer is:

natural history

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'study' is the definition.
(I know that natural history is a type of science)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for natural history that I've seen before include "Study of animals and plants" , "Gilbert White's study" , "Studying animals perhaps" , "Study of animals/plants" , "Science" .)

I've seen this clue in The Times and The Sunday Times.

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