Upsetting builder’s carrier, boy am I dumb (3)
I believe the answer is:
doh
'upsetting builder's carrier' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for doh that I've seen before include "It begins the tonic solfa" , "Note; exclamation" , "Homer Simpson's exasperated cry" , "First note of musical scale" , "First of the series at 17 Across" .)