Rolling Stone's staff do wrong, nicking last of cocaine (8)
I believe the answer is:
wanderer
'rolling stone's' is the definition.
(thesaurus)
'staff do wrong nicking last of cocaine' is the wordplay.
'staff' becomes 'wand' (wand is a kind of staff).
'do wrong' becomes 'err' (I've seen this in other clues).
'nicking' indicates putting letters inside (I've seen this in other clues).
'last of' suggests the final letters.
The last letter of 'cocaine' is 'e'.
'err' placed around 'e' is 'erer'.
'wand'+'erer'='WANDERER'
(Other definitions for wanderer that I've seen before include "Itinerant" , "Vagabond, rover" , "Peripatetic" , "Aimless traveller" , "Rambler, roamer" .)