Ring for FBI and rage laconically? (5)

I believe the answer is:
donut
'ring for fbi' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'and rage laconically?' is the wordplay.
I cannot really see how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found within the answer.
The remaining letters 'dout' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for donut that I've seen before include "ring coming across the Atlantic" , "Sugary deep-fried cake" , "American pastry" , "American treat?" , "Fast food snack" .)
