Both sides losing rag going back to prison (4)

I believe the answer is:

gaol

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'to prison' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for gaol that I've seen before include "Nick" , "See 1" , "Prison (British spelling)" , "The Ballad of Reading -- (Wilde)" , "Alternative to jail" .)

I've seen this clue in The Irish Times.

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