Some derive no use from a vessel (6)
I believe the answer is:
venous
'from a vessel' is the definition.
(from a vein - blood vessel)
'some derive no use' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'VENOUS' is hidden within 'derive no use'.
(Other definitions for venous that I've seen before include "Of blood tubes" , "Relating to blood vessels" , "through certain tubes" , "Performing the function of veins" , "Of bodily channels" .)