Had race fixed -- that's a ridiculous pretence (7)
I believe the answer is:
'a ridiculous pretence' is the definition.
(I've seen this before)
'had race fixed' is the wordplay.
'fixed' is an anagram indicator.
'hadrace' with letters rearranged gives 'CHARADE'.
'that's' is the link.
(Other definitions for charade that I've seen before include "Total pretence (as in game)" , "Game in which the answer is acted out" , "Ridiculous pretence" , "Acted riddle - pretence" , "absurd behaviour" .)