Irishman in the field of cereal production (5)
I believe the answer is:
paddy
This might be a double definition.
'irishman' is the first definition.
(Paddy is an example)
'field of cereal production' is the second definition.
'paddy' can be an answer for 'field' (paddy is a kind of field). I'm unsure of the 'of cereal production' bit.
'in the' is the link.
Can you help me to learn more?
(Other definitions for paddy that I've seen before include "Field where rice is grown" , "One regularly flooded" , "Rice in the husk" , "Wobbly" , "show of anger" .)