Favourite character cut in Beetlejuice ! (6)

I believe the answer is:
petrol
'beetlejuice' is the definition.
I can't tell whether this definition defines the answer.
'favourite character cut in' is the wordplay.
'favourite' becomes 'pet' (synonyms).
'character' becomes 'r'.
'cut in' becomes 'ol' (I can't explain this - if you can you should give a lot more credence to this answer).
'pet'+'r'+'ol'='PETROL'
Can you help me to learn more?
(Other definitions for petrol that I've seen before include "Common motor fuel" , "Common car fuel" , "Fuel for the internal combustion engine" , "Liquid fuel" , "Mineral oil refined as fuel" .)
