Like cirrus clouds (5)
I believe the answer is:
wispy
'like cirrus clouds' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for wispy that I've seen before include "Diaphanous" , "Lacking in distinction" , "Slender and delicate" , "Light and fine in texture" , "In thin strands" .)