Alan's put out by such a sound (5)
I believe the answer is:
nasal
'such a sound' is the definition.
(nasal is a kind of sound)
'alan's put out' is the wordplay.
'put out' is an anagram indicator.
'alans' anagrammed gives 'NASAL'.
'by' is the link.
(Other definitions for nasal that I've seen before include "Rhinal" , "nozzle" , "adenoids" , "Hooters" , "pinched" .)