Terrible sort of ride (4)
I believe the answer is:
dire
'terrible' is the definition.
(I know that terrible can be written as dire)
'sort of ride' is the wordplay.
'sort of' is an anagram indicator.
'ride' is an anagram of 'DIRE'.
(Other definitions for dire that I've seen before include "'Dreadful, terrible (4)'" , "Terrible; urgent" , "Really dreadful - ride on" , "Cataclysmic" , "Ominous; very bad" .)