Crossword Genius

Name a particular period to stop work (4,2,1,3)

Ross

I believe the answer is:

call it a day

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'stop work' is the definition.
(I've seen this before)

'name a particular period' is the wordplay.
'name' becomes 'call' (a name is a call-sign).
'a particular' becomes 'ita' (I can't justify this - if you can you should believe this answer much more).
'period' becomes 'day' (day is a kind of period).
'call'+'ita'+'day'='CALL IT A DAY'

'to' is the link.

Can you help me to learn more?

(Other definitions for call it a day that I've seen before include "Set the style for a 24-hour period" , "Stop work" , "Decide to stop doing something" , "Abandon work for now" , "sign off" .)

I've seen this clue in The Times.
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