Slat (4)
'slat' is the definition.
(I know that lath is a type of slat)
This is all the clue.
(Other definitions for lath that I've seen before include "Narrow strip of wood as used in trellis" , "Wooden strip for plaster" , "Strip of wood used as a base for plastering" , "Narrow thin strip of wood" , "Narrow strip of wood used as backing for plasterwork" .)
'slat' is the definition.
(I know that louver is a type of slat)
This is all the clue.