Wet huddle has a dull sound (4)
I believe the answer is:
thud
'a dull sound' is the definition.
(I've seen this in another clue)
'wet huddle has' is the wordplay.
'has' indicates a hidden word.
'THUD' is hidden in the letters of 'wet huddle'.
(Other definitions for thud that I've seen before include "Dull heavy noise" , "Noise of dull impact" , "Dull, heavy sound" , "Sound of a heavy fall" , "Sound made by impact of heavy objects" .)