Truro's head girl found in tower in a sad state (9)

I believe the answer is:

tristesse

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'a sad state' is the definition.
(tristesse means a state of melancholy sadness)

'truro's head girl found in tower' is the wordplay.
'head' indicates taking the first letters.
'girl found' becomes 'tess' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'tower' becomes 'rise' (I've seen this before).
The first letter of 'truro' is 't'.
'tess' inserted into 'rise' is 'ristesse'.
't'+'ristesse'='TRISTESSE'

'in' acts as a link.

Can you help me to learn more?

(Another definition for tristesse that I've seen is " Melancholy sadness".)

I've seen this clue in The Times.

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