Stick is father’s, note (5)
I believe the answer is:
paste
'stick' is the definition.
(I've seen this before)
'father's note' is the wordplay.
'father's' becomes 'pas' (pa is a kind of father).
'note' becomes 'te'.
'pas'+'te'='PASTE'
'is' is the link.
(Other definitions for paste that I've seen before include "It is used to stick wallpaper" , "Adhesive, for wallpaper say" , "Tapes (anag.)" , "Fix with adhesive" , "Watery adhesive" .)