Old Riga citizen in Valletta (4)

I believe the answer is:

lett

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'old riga citizen' is the definition.
'lett' can be an answer for 'citizen' (I have seen 'Baltic citizen' mean 'lett' so perhaps 'citizen' could also mean 'lett'). I am not sure about the 'old riga' bit.

'in valletta' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LETT' is hidden in the letters of 'valletta'.

Can you help me to learn more?

(Other definitions for lett that I've seen before include "Baltic citizen" , "Balt" , "northerner" , "East European" , "Native of Latvia" .)

I've seen this clue in the Evening Standard.

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