Grill fuel (7)
(Other definitions for propane that I've seen before include "A hydrocarbon gas" , "Type of gas" , "Bottle gas" , "Gas used as fuel" , "Bottled fuel gas" .)
'grill fuel' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for gas that I've seen before include "Hydrogen or methane, say" , "Piped fuel" , "Nitrogen maybe" , "Substance like air" , "American fuel" .)