Goes off to airport terminal and leaves Palermo - how maddening! (8)
I believe the answer is:
irritant
'maddening' is the definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for irritant that I've seen before include "Source of continual annoyance" , "Annoying factor" , "Something that causes annoyance and bad temper" , "Something that chafes or annoys" , "Trouble" .)