Being crude, oil's kept here without saving the planet? (9)
I believe the answer is:
indecorum
'being crude' is the definition.
(indecorum is crude behaviour)
'oil's kept here without saving the planet?' is the wordplay.
'oil's kept here' becomes 'in drum' (in an oil drum).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'saving the planet?' becomes 'eco' (as in eco-friendly).
'indrum' going around 'eco' is 'INDECORUM'.
(Other definitions for indecorum that I've seen before include "impropriety" , "Bad behaviour" , "Lack of propriety" , "Naughty behaviour" , "Improper behaviour" .)