Vessels which, coming back, may be waiting for the wind (6)
I believe the answer is:
sloops
'vessels' is the definition.
(sloop is a kind of vessel)
'coming back may be waiting for the wind' is the wordplay.
I cannot really see how this works, but
'wind' could be 'loop' (looping is a kind of winding) and 'loop' is found within the answer.
This explanation may well be incorrect...
'which' acts as a link.
Can you help me to learn more?
(Other definitions for sloops that I've seen before include "ships" , "Sailing vessels rigged fore and aft" , "sailing vessels follow" , "Boats" .)