Squabble, reversing a car in furious extremities (6)
I believe the answer is:
fracas
'squabble' is the definition.
(thesaurus)
'reversing a car in furious extremities' is the wordplay.
'reversing' shows that the letters should be reversed in order.
'in' means one lot of letters goes inside another.
'extremities' suggests removing the centre.
'furious' with its middle removed is 'fs'.
'a'+'car'='acar'
'acar' backwards is 'raca'.
'raca' put into 'fs' is 'FRACAS'.
(Other definitions for fracas that I've seen before include "Uproar - brawl" , "Noisy brawl" , "Scrap" , "Dispute" , "Noisy quarrel or disturbance" .)