... ride, and gasp uncontrollably taking a knock (9)
I believe the answer is:
disparage
'knock' is the definition.
(thesaurus)
'ride and gasp uncontrollably taking a' is the wordplay.
'and' says to put letters next to each other (I've seen this in other clues).
'uncontrollably' indicates an anagram (I've seen this in other clues).
'taking' indicates putting letters inside.
'ride' put after 'gasp' is 'gaspride'.
'gaspride' with letters rearranged gives 'disprage'.
'disprage' going around 'a' is 'DISPARAGE'.
(Other definitions for disparage that I've seen before include "I grasped a change to belittle" , "Slight" , "Belittled" , "Scorn" , "Run down" .)