It should be kept in Delaware (3)
I believe the answer is:
law
'it should be' is the definition.
The definition suggests a singular noun which matches the answer.
'in delaware' is the wordplay.
'in' says the answer is hidden in the clue.
'LAW' is hidden within 'delaware'.
'kept' acts as a link.
Can you help me to learn more?
(Other definitions for law that I've seen before include "Set of rules laid down by authority" , "Rule prohibiting certain actions" , "'Possession is nine points of the ...'" , "Body of rules of conduct for a society" , "Commandment" .)