Corn one put in puzzling place (5)
I believe the answer is:
maize
'corn' is the definition.
(I know that corn can be written as Maize)
'one put in puzzling place' is the wordplay.
'one' becomes 'I' (Roman numeral).
'put in' indicates putting letters inside.
'puzzling place' becomes 'maze' (a maze is like a puzzle).
'i' going within 'maze' is 'MAIZE'.
(Other definitions for maize that I've seen before include "Corn cob" , "Corn-cob cereal" , "Something cultivated" , "Corncob plant" , "Sweet corn" .)