In need of oil to be so clean? (7)
I believe the answer is:
squeaky
'in' is the definition.
Both the answer and definition are adjectives. Maybe you can see a link between them that I don't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for squeaky that I've seen before include "Above reproach" , "Sounding like a mouse; completely (clean)" , "High-pitched" , "In need of some oil" , "- Clean means virtuous" .)