Some retro vehicles in prized collection (5)
I believe the answer is:
trove
'prized collection' is the definition.
(as in a treasure trove)
'some retro vehicles in' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'TROVE' is hidden within 'retro vehicles in'.
(Other definitions for trove that I've seen before include "hidden valuables" , "Finds" , "Collection of valuables" , "Collection of treasures" , "Hidden treasure for voter" .)