Sleek and slender (6)
I believe the answer is:
svelte
'sleek and slender' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for svelte that I've seen before include "Slim and attractive" , "Slender or sleek" , "Elegant and of slender build" , "Polished" , "free" .)