Solution for 8 July cryptic crossword clue

Break off the betrothal? (9)

Solution – disengage

If you get engaged you are, in oldy worldy language, betrothed.  If you break the engagement, you can't say you got "dis-engaged" since it isn't a real word.  But because there is a question mark at the end of the clue, you are given a hint that everything may not be proper English.

So if you break off from something you can "disengage" from it.

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