Game hedgehog going at some speed (5)
I believe the answer is:
sonic
I believe this clue is a double definition.
'game hedgehog' is the first definition.
(video game character Sonic the Hedgehog)
'going at some speed' is the second definition.
(as in a sonic boom)
(Other definitions for sonic that I've seen before include "Relating to sound waves" , "Relating to the speed of sound" , "Kind of boom" , "Using waves" , "Type of boom" .)