Note Yorkshire's opener becoming short-tempered (9)
I believe the answer is:
crotchety
'short-tempered' is the definition.
(I've seen this before)
'note yorkshire's opener' is the wordplay.
'note' becomes 'crotchet' (musical note).
'opener' suggests taking the first letters.
The first letter of 'yorkshire' is 'y'.
'crotchet'+'y'='CROTCHETY'
'becoming' is the link.
(Other definitions for crotchety that I've seen before include "Cross" , "Irritable" , "Short-tempered" , "Ill-tempered" , "Difficult" .)