Unreasonably unwilling to change (8)
I believe the answer is:
stubborn
'unreasonably unwilling to change' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for stubborn that I've seen before include "Obstinate, unwilling to yield" , "Obstinate, bullheaded" , "small boat in Loire, good for going around river" , "Tenaciously unwilling to yield" , "Inflexible" .)