Engineering manual for student once (6)

I believe the answer is:

alumna

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'student once' is the definition.
I can't tell whether this defines the answer.

'engineering manual' is the wordplay.
'engineering' indicates an anagram (letters manipulated or engineered).
'manual' is an anagram of 'ALUMNA'.

'for' acts as a link.

Can you help me to learn more?

(Other definitions for alumna that I've seen before include "She studied" , "Harvard graduate" , "Manual (anag) - old girl" , "Female graduate" , "Female former pupil" .)

I've seen this clue in The Guardian.

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