President Jimmy lost leadership over one aluminium highway (8)
I believe the answer is:
arterial
'highway' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for arterial that I've seen before include "Like certain vessels" , "Relating to major routes" , "Main (road); of blood tube" , "like the bloody tube!" , "A trailer (anag.)" .)