Rare slip upset quid pro quo (8)

I believe the answer is:

reprisal

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'quid pro quo' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?

'rare slip upset' is the wordplay.
'upset' is an anagram indicator.
'rare'+'slip'='rareslip'
'rareslip' with letters rearranged gives 'REPRISAL'.

Can you help me to learn more?

(Other definitions for reprisal that I've seen before include "Retaliatory deed" , "revenge attack" , "Counterattack" , "hitting back" , "compensation" .)

I've seen this clue in The Telegraph.

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