Group of drivers checking vehicle's lack of coordination (6)
I believe the answer is:
ataxia
'lack of coordination' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'group of drivers checking vehicle's' is the wordplay.
'group of drivers' becomes 'aa' (Automobile Association).
'checking' means one lot of letters goes inside another (check can mean to control or arrest).
'vehicle' becomes 'taxi' (taxi is a kind of vehicle).
'aa' placed around 'taxi' is 'ATAXIA'.
Can you help me to learn more?
(Other definitions for ataxia that I've seen before include "Inability to manoeuvre" , "motor problem" , "Inability to coordinate voluntary muscle movements" , "Inability to coordinate actions" .)