Climber using salesperson's transport (10,3)
I believe the answer is:
travellers joy
'climber' is the definition.
(I've seen this before)
'salesperson's transport' is the wordplay.
'salesperson's' becomes 'traveller's' (travelling salesperson).
'transport' becomes 'joy' (both can mean bliss or ecstasy).
'travellers'+'joy'='TRAVELLERS JOY'
'using' acts as a link.
(Other definitions for travellers joy that I've seen before include "Clematis" , "Climber" , "old man's beard" .)