That's the end of holiday working (3)

I believe the answer is:

yon

'that's' is the definition.
(archaic term meaning 'that')

'the end of holiday working' is the wordplay.
'the end of' says to take the final letters.
'working' becomes 'on'.
The final letter of 'holiday' is 'y'.
'y'+'on'='YON'

(Another definition for yon that I've seen is " Those Scots".)

I've seen this clue in The Times.

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