New postal centre in the field of agriculture (4)
I believe the answer is:
oats
'the field of agriculture' is the definition.
I can't tell whether this definition defines the answer.
'new postal centre' is the wordplay.
'new' becomes 'oat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'postal' becomes 'berserk' (I've seen this in another clue).
'centre' indicates the central letters.
The middle of 'berserk' is 's'.
'oat'+'s'='OATS'
'in' is the link.
Can you help me to learn more?
(Other definitions for oats that I've seen before include "Seed grasses" , "Basis of porridge" , "Porridge ingredients" , "Young folk might sow wild ones" , "Hardy cereals eaten by horses" .)