Note the brick-carrier's upset (3)
I believe the answer is:
doh
'note' is the definition.
(alternative spelling of 'do' as in do re mi)
'the brick-carrier's upset' is the wordplay.
'the brick-carrier' becomes 'hod' (type of trough used for carrying bricks).
'upset' is a reversal indicator.
'hod' back-to-front is 'DOH'.
(Other definitions for doh that I've seen before include "The note C" , "First note of major scale in music" , "First of the series at 17 Across" , "annoyed expression" , "First and eighth note in tonic sol-fa" .)