Ancient Aussie car won't start! (5)
I believe the answer is:
olden
'ancient' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for olden that I've seen before include "Led on (anag)" , "Former, past" , "(Of days) in the long distant past!" , "Out of date" , "Of past (times)" .)