The winner picks up first-class plum
I believe the answer is:
victoria
'plum' is the definition.
(I've seen this before)
'the winner picks up first-class' is the wordplay.
'the winner' becomes 'victor' (synonyms).
'picks up' says the letters should be written backwards.
'first class' becomes 'ai' (A1 - top quality).
'ai' written backwards gives 'ia'.
'victor'+'ia'='VICTORIA'
(Other definitions for victoria that I've seen before include "Capital of the Seychelles" , "One of the Beckhams" , "Queen (eighteen thirty seven to nineteen hundred and one)" , "Old carriage" , "Girl" .)