Passenger gets left to erupt (5)
I believe the answer is:
flare
'to erupt' is the definition.
(synonyms)
'passenger gets left' is the wordplay.
'passenger' becomes 'fare' (fare is a kind of passenger).
'gets' indicates putting letters inside (gets can mean captures or absorbs).
'left' becomes 'l' (common abbreviation).
'fare' going around 'l' is 'FLARE'.
(Other definitions for flare that I've seen before include "Warning light" , "Sudden burst of flame" , "Burn with sudden brightness" , "Burst into sudden activity or anger" , "Spread" .)