Dull sound from detachment huddled (4)
I believe the answer is:
thud
'dull sound' is the definition.
(I've seen this in another clue)
'from detachment huddled' is the wordplay.
'from' indicates a hidden word.
'THUD' is hidden in the letters of 'detachment huddled'.
(Other definitions for thud that I've seen before include "Low dull sound as of blow" , "Sound of a heavy fall" , "Clonk" , "Clunk" , "Sound of heavy blow" .)