Crossword Genius

Brief note after sex (4,2)

Ross

I believe the answer is:

post-it

'brief note' is the definition.
(brand name for a type of note paper)

'after sex' is the wordplay.
'after' becomes 'post' (I've seen this before).
'sex' becomes 'it' (a common euphemism).
'post'+'it'='POST-IT'

I've seen this clue in The Guardian.
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