Airline against providing fatty food (5)
I believe the answer is:
bacon
'fatty food' is the definition.
(bacon is fatty)
'airline against' is the wordplay.
'airline' becomes 'BA' (British Airways).
'against' becomes 'con' (as in pros and cons, for and against).
'ba'+'con'='BACON'
'providing' is the link.
(Other definitions for bacon that I've seen before include "gammon" , "famous artist" , "Painter; cured meat" , "The meat to bring home for success" , "See 9" .)