Domestic role, mostly as engine driver? (6)
I believe the answer is:
petrol
'engine driver?' is the definition.
(the fuel that drives the engine)
'domestic role mostly' is the wordplay.
'domestic' becomes 'pet' (I can't justify this - if you can you should give a lot more credence to this answer).
'mostly' means to remove the last letter (most but not all of the word).
'role' with its last letter taken off is 'rol'.
'pet'+'rol'='PETROL'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for petrol that I've seen before include "Common motor fuel" , "Liquid fuel" , "Mineral oil refined as fuel" , "Common car fuel" , "Fuel for road vehicles" .)