Jot letter from Athens (4)

I believe the answer is:

iota

This clue is a double definition.

'jot' is the first definition.
(thesaurus)

'letter from athens' is the second definition.
(Greek letter)

(Other definitions for iota that I've seen before include "Tiny bit" , "Ninth Greek character" , "Grain" , "Gr. letter; small amount" , "Ninth letter of Greek alphabet, small amount" .)

I've seen this clue in The Times.

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