Fill up tyre on VW traveller (5,4)
I believe the answer is:
marco polo
'traveller' is the definition.
(13th-century explorer)
'fill up tyre on vw' is the wordplay.
'fill' becomes 'cram' (synonyms).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'tyre' becomes 'O' (O resembles a wheel).
'on' is a charade indicator (letters next to each other).
'vw' becomes 'polo' (type of Volkswagen).
'cram' reversed gives 'marc'.
'marc'+'o'+'polo'='MARCO POLO'
(Other definitions for marco polo that I've seen before include "sheep" , "Italian traveller" , "Venetian merchant, who travelled to China" , "Great Venetian explorer of China and Asia in 14th century" , "Historic trader" .)