Ollie's partner, famous comedian, in one-seater carriage (8)
I believe the answer is:
stanhope
'one-seater carriage' is the definition.
(type of carriage)
'ollie's partner famous comedian' is the wordplay.
'ollie's partner' becomes 'stan' (as in Stan Laurel and Oliver Hardy).
'famous comedian' becomes 'hope' (US comedian Bob Hope).
'stan'+'hope'='STANHOPE'
'in' is the link.
(Other definitions for stanhope that I've seen before include "old-fashioned conveyance" , "carriage that has seat only for one" , "Phaetons can be turned into a light open one-seater carriage" , "Light horse-drawn carriage; Nineteen across (anag.)" , "It may have only two wheels" .)