Unseen aphids deprived of sap, possibly (3)

I believe the answer is:

hid

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'unseen' is the definition.
The answer and definition are different parts of speech. However, adjectives and past participle verbs sometimes define each other.

'aphids deprived of sap possibly' is the wordplay.
'HID' is hidden within the letters.
But, I am unsure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for hid that I've seen before include "Stayed out of sight" , "Remained out of sight" , "wanted to be sought?" , "Concealed (oneself?)" , "Concealed, kept secret" .)

I've seen this clue in the Evening Standard.

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