Geezer (4)
I believe the answer is:
coot
'geezer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for coot that I've seen before include "Waterfowl" , "Black waterbird" , "Stupid or eccentric man" , "Slow-flying birds, duck-like" , "Blackish aquatic bird" .)