Third person by eighth vehicle? It may be fruitful (10,4)

I believe the answer is:

gooseberry bush

'it may be fruitful' is the definition.
(a gooseberry bush produces fruit)

'third person by eighth vehicle?' is the wordplay.
'third person' becomes 'gooseberry' (gooseberry can mean an extra person with a couple).
'by' means one lot of letters go next to another.
'eighth vehicle?' becomes 'bush' (bus H with be 8th after bus A, bus B etc.).
'gooseberry'+'bush'='GOOSEBERRY BUSH'

(Another definition for gooseberry bush that I've seen is " proves prickly".)

I've seen this clue in The Guardian.

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