Roughly in charge of car, careering (5)
I believe the answer is:
circa
'roughly' is the definition.
(I've seen this before)
'charge of car careering' is the wordplay.
'charge of' becomes 'ci' (I can't justify this - if you can you should believe this answer much more).
'careering' indicates an anagram (careering can mean moving violently).
'car' is an anagram of 'rca'.
'ci'+'rca'='CIRCA'
'in' is the link.
Can you help me to learn more?
(Other definitions for circa that I've seen before include "Close to" , "Costa del Sol city" , "About (regarding dates)" , "Roughly" , "About (a time)" .)