Moor in Arabian chorus (6)
I believe the answer is:
anchor
'moor' is the definition.
(I've seen this before)
'in arabian chorus' is the wordplay.
'in' says the answer is hidden in the clue.
'ANCHOR' can be found hidden inside 'arabian chorus'.
(Other definitions for anchor that I've seen before include "Horse-breeding farm" , "Firmly secure; moor" , "Stabilise" , "Device to keep ship in place" , "No arch when you drop it, oddly" .)