Lack of knowledge in one racing around (9)
I believe the answer is:
ignorance
'lack of knowledge' is the definition.
(I've seen this before)
'one racing around' is the wordplay.
'around' indicates anagramming the letters.
'one'+'racing'='oneracing'
'oneracing' with letters rearranged gives 'IGNORANCE'.
'in' is the link.
(Other definitions for ignorance that I've seen before include "may be considered bliss" , "bliss, they say" , "Not knowing" , "Unintelligence" , "Ken lacking" .)