Birds, for example, disturbed rest (6)
I believe the answer is:
'birds' is the definition.
(egret is a kind of bird)
'example disturbed rest' is the wordplay.
'example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'disturbed' indicates an anagram (the order of letters is disturbed).
'rest' is an anagram of 'rets'.
'for' is the link.
(Other definitions for egrets that I've seen before include "Greets in way of certain herons (" , "creatures" , "Kind of herons with long white feathers" , "Greets like certain herons" , "Fliers" .)