Awesome time (3)
(Other definitions for gas that I've seen before include "What's needed to drive" , "eg CO2" , "American fuel" , "Americans' petrol" , "rabbit" .)
'awesome time' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for blast that I've seen before include "Report" , "Blow up or swear" , "Damn - explosion" , "slate" , "Mild expletive - sharp explosion" .)