Cold sponge's bottom needs to be on top (5)
I believe the answer is:
aloof
'cold' is the definition.
(both can mean distant)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for aloof that I've seen before include "Unpleasantly cold" , "Withdrawn, distant" , "Remote in manner" , "Displaying supercilious reserve" , "A fool being cool and remote" .)