Note making one irritable? Not quite (8)
I believe the answer is:
crotchet
'note' is the definition.
(crotchet is a kind of note)
'one irritable? not quite' is the wordplay.
'one irritable?' becomes 'crotchety' (I've seen this before).
'not quite' means to remove the last letter.
'crotchety' with its last letter removed is 'CROTCHET'.
'making' is the link.
(Other definitions for crotchet that I've seen before include "Two quavers as one note" , "Musical note equal to half a minim" , "perverse notion" , "A note in music equal to half a minim" , "One in bar" .)