Motorised or not, it isn't all that fast (7)
I believe the answer is:
scooter
'it isn't all that fast' is the definition.
The definition suggests a singular noun which matches the answer.
'motorised or not' is the wordplay.
I cannot quite understand how this works, but
'not' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
The remaining letters 'scoter' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for scooter that I've seen before include "Child's two-wheeled vehicle" , "To score (anag)" , "Two-wheeled motor vehicle" , "Small motorcycle" , "Traveller" .)