NT woman featured in holy diagram (5)

I believe the answer is:

lydia

I'm a little stuck... Click here to teach me more about this clue!

'nt woman featured' is the definition.
I can't judge whether this definition defines the answer.

'in holy diagram' is the wordplay.
'in' says the answer is hidden in the clue.
'LYDIA' is hidden within 'holy diagram'.

Can you help me to learn more?

(Other definitions for lydia that I've seen before include "girl" , "Old country" , "Woman" , "where Croesus was king" , "'Love for --' (H.E. Bates)" .)

I've seen this clue in The Times.

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