Clip quiet organ (5)
I believe the answer is:
shear
'clip' is the definition.
(I know that shear is a more specific form of the action clip)
'quiet organ' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'organ' becomes 'ear' (the ear is an organ).
'sh'+'ear'='SHEAR'
(Other definitions for shear that I've seen before include "shave" , "Cut sheep's woll with large scissors" , "Remove sheep's wool" , "Cut wool off (a sheep)" , "Clip a sheep" .)