River and lake bird (5)
I believe the answer is:
ousel
'bird' is the definition.
(ousel is a kind of bird)
'river and lake' is the wordplay.
'river' becomes 'ouse' (Yorkshire river).
'and' is a charade indicator (letters next to each other).
'lake' becomes 'l'.
'ouse'+'l'='OUSEL'
(Other definitions for ousel that I've seen before include "it goes flying" , "Louse (anag.); blackbird" , "Dark-faced type of yore" , "dipper" , "Bird similar to blackbird" .)