Sleek, polished (6)
I believe the answer is:
smooth
This clue is a double definition.
'sleek' is the first definition.
(similar in meaning)
'polished' is the second definition.
(I've seen this before)
(Other definitions for smooth that I've seen before include "Not rough or wrinkled" , "Having even surface with no projections" , "Glossy" , "Even; without jerks" , "Easy" .)