Going out one aunt takes the back seat of a car (7)
I believe the answer is:
tonneau
'the back seat of a car' is the definition.
I can't judge whether this definition defines the answer.
'going out one aunt' is the wordplay.
'going out' indicates an anagram (out can mean wrong or inaccurate).
'one'+'aunt'='oneaunt'
'oneaunt' anagrammed gives 'TONNEAU'.
'takes' is the link.
Can you help me to learn more?
(Other definitions for tonneau that I've seen before include "Protective cover for open car" , "Seat cover" , "Rear of an open carriage" , "back of the car" , "Part of open car behind front seats" .)