Waterfowl heading away from dam site (4)
I believe the answer is:
swan
'waterfowl' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for swan that I've seen before include "Flighty" , "Cob - pen" , "Whooper or trumpeter?" , "black, in 7th" , "Long-necked water bird" .)