Symbol of lightness (7)
I believe the answer is:
feather
'symbol of lightness' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for feather that I've seen before include "Part of covering of bird" , "The fear (anag) - type of bed" , "Part of a bird's plumage" , "manipulate oar" , "In your cap, this represents an achievement" .)