They may be light, but you can't really raise them (4)
I believe the answer is:
rays
'they' is the definition.
Both the answer and definition are plural nouns.
Maybe they are linked in a way I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for rays that I've seen before include "Fish with wing-shaped fins and long tails" , "Columns of light or heat" , "Sunbeams" , "Flat fish" , "shafts" .)