Stubborn dope stopping on the way (12)
I believe the answer is:
intransigent
'stubborn' is the definition.
(I've seen this before)
'dope stopping on the way' is the wordplay.
'dope' becomes 'gen' (I've seen this in other clues).
'stopping' indicates putting letters inside (stopping can mean blocking a gap).
'on the way' becomes 'intransit' (I've seen this before).
'gen' going inside 'intransit' is 'INTRANSIGENT'.
(Other definitions for intransigent that I've seen before include "Unlikely to budge" , "Impervious to persuasion or reason" , "unwilling to compromise" , "Not prepared to adapt or compromise" , "Hardliner" .)