He has dog rolling barrel (8)
I believe the answer is:
hogshead
'barrel' is the definition.
(hogshead is a kind of barrel)
'he has dog rolling' is the wordplay.
'rolling' indicates anagramming the letters.
'he'+'has'+'dog'='hehasdog'
'hehasdog' with letters rearranged gives 'HOGSHEAD'.
(Other definitions for hogshead that I've seen before include "Much wine" , "Provider of brawn" , "lot of drink" , "barrel" , "Large cask for alcohol" .)