The most common and most likely answer to this crossword clue is the 7 letter word TONNEAU
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More clues leading to the result TONNEAU
- Oiled nut, one securing a vintage car part
- Cover provided by EU and NATO repositioning around November
- Heavyweight gold back seat cover
- Thousand-kilogramme gold cover for car
- Rear seating compartment/unit with awesome upholstery primarily
- Back seat of auto's bouncing carrying nine — one got tossed out
- 1000kg gold for car cover
Buddy explains!

The straight part
We know that "Back seat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case back seat = tonneau.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TONNEAU mean?
TONNEAU noun- The rear body or compartment of some types of motor vehicle, especially one containing seats for passengers.
- An old-style open passenger vehicle with a tonneau (rear compartment with seats).
- A protective covering which may be secured over the exposed portion of a motor vehicle, such as the seating area of an open sports car or the back of a pickup truck.