Strangely silent coves (6)
I believe the answer is:
inlets
'coves' is the definition.
('inlet' can be a synonym of 'cove')
'strangely silent' is the wordplay.
'strangely' is an anagram indicator.
'silent' with letters rearranged gives 'INLETS'.
(Other definitions for inlets that I've seen before include "Small bays of silent kind" , "Bays or coves" , "Silent kind of water channels" , "Silent as sea entries to land" , "Silent sort of sea strips" .)