Rotten finish upset (6)

I believe the answer is:

offend

'upset' is the definition.
(offend can mean to upset or insult)

'rotten finish' is the wordplay.
'rotten' becomes 'off' (rotten food is 'off').
'finish' becomes 'end' (come to an end).
'off'+'end'='OFFEND'

(Other definitions for offend that I've seen before include "Affront - break the law" , "Be displeasing to" , "Upset; transgress" , "Act in disregard of the law" , "cause displeasure or do wrong" .)

I've seen this clue in The Times.

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