Stated refusal, as Arab for one may do (5)
I believe the answer is:
neigh
'as arab for one may do' is the definition.
(I know that horses often neigh)
'stated refusal' is the wordplay.
'stated' indicates a 'sounds like' (homophone) clue.
'refusal' becomes 'nay' (archaic word for 'no').
'nay' is a homophone of 'NEIGH'.
(Other definitions for neigh that I've seen before include "Mare's cry, e.g." , "Horse's cry" , "Whinnying sound" , "sound from the stable?" , "Whinnying noise" .)