Sensory organ captures one sound (5)
I believe the answer is:
noise
'sound' is the definition.
(a noise is a sound)
'sensory organ captures one' is the wordplay.
'sensory organ' becomes 'nose' (organ used for smell).
'captures' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'nose' going around 'i' is 'NOISE'.
(Other definitions for noise that I've seen before include "Unwanted sound" , "Loud sound; bruit" , "Virgil's birthplace" , "Clamour" , "Sound - gossip" .)