I am presuming (quite probably wrongly! by the thread title, that the answer will be the name of a river.
There is a River Croe in North West Scotland.
There is a Crow River in Minnesota.
I cant see where "groyne" would come in?
Also a River Coe in Scotland, plus "r" for river.
If your letters are wrong, then Mole looks bang on.
I am flummoxed!