Heron flying to find river (5)
I believe the answer is:
rhone
'river' is the definition.
(Rhone River is an example)
'heron flying' is the wordplay.
'flying' indicates anagramming the letters.
'heron' anagrammed gives 'RHONE'.
'to find' acts as a link.
(Other definitions for rhone that I've seen before include "Fr. river and wine" , "French flower" , "Major French river, rising in Switzerland" , "wherein runs rain in Arbroath" , "department" .)