On motorway, football team consumes gallon bottle (6)
I believe the answer is:
magnum
'bottle' is the definition.
(magnum is a kind of bottle)
'on motorway football team consumes gallon' is the wordplay.
'on' says to put letters next to each other.
'motorway' becomes 'M' (as in motorway names - M1, M4 etc).
'football team' becomes 'man u' (short for Manchester United).
'consumes' means one lot of letters goes inside another.
'gallon' becomes 'g' (abbreviation for the unit of liquid).
'manu' placed around 'g' is 'magnu'.
'm' after 'magnu' is 'MAGNUM'.
(Other definitions for magnum that I've seen before include "Double-sized wine bottle" , "lots of wine" , "a lot of bottle!" , "1 1/2 litre champagne bottle" , "Arm" .)