Butterfly catcher (3)
I believe the answer is:
net
'butterfly catcher' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for net that I've seen before include "It's see-through" , "Open-meshed material (used for catching things?)" , "Mesh; entrap" , "Final profit when all overheads have been deducted" , "Catch -- after all deductions" .)