Cloth worker supported by a surprisingly smart court officer (8,2,4)
I believe the answer is:
sergeant at arms
'court officer' is the definition.
(official in a court or legislative body)
'cloth worker supported by a surprisingly smart' is the wordplay.
'cloth' becomes 'serge' (serge is a kind of cloth).
'worker' becomes 'ant' (worker is a type of ant).
'supported by' means one lot of letters go next to another (in a down clue, some letters hold up others).
'surprisingly' indicates anagramming the letters (a surprising ordering of the letters).
'smart' with letters rearranged gives 'tarms'.
'serge'+'ant'+'a'+'tarms'='SERGEANT-AT-ARMS'
(Other definitions for sergeant at arms that I've seen before include "Officer of a legislative body maintaining order (G, not J)" , "officer trying to keep order" .)