Rather sour tonic tends to go off (10)

I believe the answer is:

discontent

'rather sour' is the definition.

'tonic tends to go off' is the wordplay.
'to go off' indicates anagramming the letters.
'tonic'+'tends'='tonictends'
'tonictends' with letters rearranged gives 'DISCONTENT'.

(Other definitions for discontent that I've seen before include "Lack of satisfaction" , "Dissatisfaction" , "blighted Gloucester's winter" , "Bad feelings" , "Now is the winter of our - (Rich.III)" .)

I've seen this clue in The Times.

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