Tax on tasty dump, perhaps (5,4)
I believe the answer is:
stamp duty
'tax' is the definition.
(stamp duty is a kind of tax)
'on tasty dump perhaps' is the wordplay.
'on' is a charade indicator (letters next to each other).
'perhaps' indicates anagramming the letters.
'tasty' put after 'dump' is 'dumptasty'.
'dumptasty' with letters rearranged gives 'STAMP-DUTY'.
(Other definitions for stamp duty that I've seen before include "House purchase levy" , "Tax receipted by affixing paper seal to deed" , "House-buying tax" , "Tax collected on legal documents" , "Kind of tax as on house purchase - or letter post?" .)