Hark! It's oddly silent (6)
I believe the answer is:
listen
'hark' is the definition.
(I know that hark is a more specific form of the action listen)
'oddly silent' is the wordplay.
'oddly' indicates an anagram.
'silent' is an anagram of 'LISTEN'.
'it's' is the link.
(Other definitions for listen that I've seen before include "Pay attention and hear" , "Take notice" , "16 (anag.)" , "Hark!" , "Make an effort to hear" .)