Inferior porcelain in place of horse trials (9)
I believe the answer is:
badminton
'place of horse trials' is the definition.
(Badminton Horse Trials)
'inferior porcelain' is the wordplay.
'inferior' becomes 'bad' (similar in meaning).
'porcelain' becomes 'Minton' (porcelain made by the company Mintons).
'bad'+'minton'='BADMINTON'
'in' acts as a link.
(Other definitions for badminton that I've seen before include "Game played with rackets" , "Game played with a shuttlecock" , "Racket sport" , "22 Across sport" , "One sport" .)