A political clown and jester initially slipping over in oil (6)
I believe the answer is:
Here is my best explanation:
'oil' is the definition.
(I have seen 'Cosmetic oil ' mean 'jojoba' so perhaps 'oil' could also mean 'jojoba')
'a political clown and jester initially slipping over' is the subsidiary indication.
'political clown' becomes 'bojo' (nickname of Boris Johnson).
'and' means one lot of letters go next to another.
'initially' says to take the initial letters.
'slipping over' says the letters should be written in reverse.
The initial letter of 'jester' is 'j'.
'abojoj' in reverse letter order is 'jojoba'.
'in' is the link.
(Other definitions for jojoba that I've seen before include "North American shrub whose oil is used in cosmetics", "Cosmetic oil", "desert plant", "Oil used in cosmetics", "plant oil", "Seedy desert native" and "tree".)