McLuhan failing to start damaged motorboat (6)
I believe the answer is:
launch
'motorboat' is the definition.
(launch is a kind of motorboat)
'mcluhan failing to start damaged' is the wordplay.
'failing to start' means to remove the first letter.
'damaged' indicates an anagram.
'mcluhan' with its initial letter taken away is 'cluhan'.
'cluhan' with letters rearranged gives 'LAUNCH'.
(Other definitions for launch that I've seen before include "Send out; motor boat" , "starter?" , "Rocket journey's starting point" , "pleasure-boat" , "Send off (a rocket)" .)