Little coffee in same diets when modified (9)

I believe the answer is:

demitasse

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'little coffee' is the definition.
'demitasse' can be an answer for 'coffee' (demitasse is a kind of coffee). I'm unsure of the 'little' bit.

'same diets when modified' is the wordplay.
'same diets' can be anagrammed to 'DEMITASSE'.
However, I'm not clear how this is indicated.

'in' acts as a link.

Can you help me to learn more?

(Other definitions for demitasse that I've seen before include "Coffee-cup" , "Small cup for black coffee" , "little cup" .)

I've seen this clue in the Sydney Morning Herald.

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