Tops of waves (6)
I believe the answer is:
crests
'tops of waves' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for crests that I've seen before include "Emblems of families" , "summits" , "Topmost ridges of mountains" , "Tufts on birds' heads, or tops of waves" .)