Hacks rave about bag (9)
I believe the answer is:
haversack
'bag' is the definition.
(I know that haversack is a type of bag)
'hacks rave about' is the wordplay.
'about' indicates an anagram.
'hacks'+'rave'='hacksrave'
'hacksrave' anagrammed gives 'HAVERSACK'.
(Other definitions for haversack that I've seen before include "Carrier" , "Backpack" , "Item of luggage" , "Strong bag slung over the shoulder" .)