Cap of ointment for your mouth (8)
I believe the answer is:
balmoral
'cap' is the definition.
(I know that Balmoral is a type of cap)
'ointment for your mouth' is the wordplay.
I cannot quite see how this works, but
'ointment' could be 'balm' (synonyms) and 'balm' is found in the answer.
The remaining letters 'oral' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for balmoral that I've seen before include "British royal summer residence" , "Scottish holiday residence of British royals" , "somewhere in Scotland" , "Scottish royal home" , "Royal holiday residence on the River Dee" .)