Greek characters leaving the job unfinished (6)

I believe the answer is:

thetas

'greek characters' is the definition.

'the job unfinished' is the wordplay.
'job' becomes 'task' ('task' can be a synonym of 'job').
'unfinished' means to remove the last letter.
'task' with its last letter taken away is 'tas'.
'the'+'tas'='THETAS'

'leaving' acts as a link.

(Another definition for thetas that I've seen is " Athenian characters".)

I've seen this clue in The Times.

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