Blue blood vessels? (6)
I believe the answer is:
yachts
'blue blood vessels?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yachts that I've seen before include "Racing or cruising boats" , "Vessels propelled by sail or power" , "Light sailing-vessels" , "Pleasure boats" , "Sailing vessels" .)