Finished tarts after good fish (7)

I believe the answer is:

guppies

'fish' is the definition.
(guppy is a type of fish)

'finished tarts after good' is the wordplay.
'finished' becomes 'up' (eg 'time's up' means the time is finished).
'tarts' becomes 'pies' (I've seen this before).
'after' says to put letters next to each other.
'good' becomes 'g' (abbreviation).
'up'+'pies'='uppies'
'uppies' after 'g' is 'GUPPIES'.

I've seen this clue in The Times.

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