Emergency for journey to relieve ancient city (5,4)
I believe the answer is:
spare tyre
'emergency for journey' is the definition.
The definition suggests a singular noun which matches the answer.
'relieve ancient city' is the wordplay.
'relieve' becomes 'spare' (sparing is a kind of relieving).
'ancient city' becomes 'tyre' (ancient city in modern-day Lebanon).
'spare'+'tyre'='SPARE TYRE'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for spare tyre that I've seen before include "Gastric band" , "Extra bit of fat" , "Something needed for flat" , "Extra weight round one's middle" , "Something kept for the flat" .)