Coves that are strangely silent (6)
I believe the answer is:
inlets
'coves' is the definition.
('inlet' can be a synonym of 'cove')
'are strangely silent' is the wordplay.
'are strangely' is an anagram indicator.
'silent' is an anagram of 'INLETS'.
'that' is the link.
(Other definitions for inlets that I've seen before include "Silent kind of water channels" , "Silent as sea entries to land" , "Narrow channels of water running from sea or river" , "Small bays of silent kind" , "Silent strips of water" .)