Drying oven
I think it could be either:
'drying oven' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for kiln that I've seen before include "Kind of oven" , "Potter's Friend" , "Oven for burning lime" , "Industrial oven" , "Drying furnace" .)
'drying oven' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oast that I've seen before include "Hop-kiln" , "Cooker" , "Drying house" , "Oven for hops" , "Hop-drying kiln" .)