Netting; engage (4)
I believe the answer is:
mesh
I believe this clue is a double definition.
'netting' is the first definition.
(I've seen this in another clue)
'engage' is the second definition.
(I know that engage can be written as mesh)
(Other definitions for mesh that I've seen before include "Lattice" , "Undeviating" , "Netting; engage" , "Become entangled - become engaged" , "Trap" .)