Car slightly deficient facing ban -- this could strengthen its frame (7)
I believe the answer is:
rollbar
'this could strengthen its frame' is the definition.
The definition suggests a singular noun which matches the answer.
'car slightly deficient facing ban' is the wordplay.
I cannot quite see how this works, but
'ban' could be 'bar' (I've seen this before) and 'bar' is found within the answer.
The remaining letters 'roll' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rollbar that I've seen before include "Maybe one resisting turnover" , "Sports car safety device" , "Safety frame used on motor sport vehicles" , "safety feature on vehicle" , "Sports car safety feature" .)