Removal of cars not a bit unusual (11)
I believe the answer is:
abstraction
'removal' is the definition.
(I know that abstraction is a type of removal)
'cars not a bit unusual' is the wordplay.
'unusual' is an anagram indicator.
'cars'+'not'+'a'+'bit'='carsnotabit'
'carsnotabit' anagrammed gives 'ABSTRACTION'.
'of' acts as a link.
(Other definitions for abstraction that I've seen before include "form of treatment" , "withdrawing" , "That's the general idea" , "theory" , "Theoretical concept - removal" .)