Wandering single-prong diatribe (9)
I believe the answer is:
itinerant
'wandering' is the definition.
(I've seen this before)
'single-prong diatribe' is the wordplay.
'single' becomes 'I' (I as in one).
'prong' becomes 'tine' (tine is a kind of prong).
'diatribe' becomes 'rant' (I've seen this in other clues).
'i'+'tine'+'rant'='ITINERANT'
(Other definitions for itinerant that I've seen before include "Travelling around" , "Nomadic" , "Wandering from place to place" , "(Person) on the move" , "Old labourer/traveller who travelled from place to place" .)