Hit and stab in back (4-3)

I believe the answer is:

sell-out

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'stab in back' is the definition.
'sell out' can be an answer for 'stab' (thesaurus). I'm not certain of the 'in back' bit.

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for sell-out that I've seen before include "When all tickets are booked in advance" , "Betrayal" , "Event with no further ticket availability" , "successful show" .)

I've seen this clue in The Times.

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