Leave extremely disagreeable role (6)
I believe the answer is:
depart
'leave' is the definition.
(I know that leave can be written as depart)
'extremely disagreeable role' is the wordplay.
'extremely' suggests removing the centre (only the extremes of the word are used).
'role' becomes 'part' (eg a part or role in a film).
'disagreeable' with its centre removed is 'de'.
'de'+'part'='DEPART'
(Other definitions for depart that I've seen before include "Start out" , "Petard (anag.)" , "Retire from" , "Prated (anag.)" , "Stray" .)