Swiss river heron in distress (5)
I believe the answer is:
rhone
'swiss river' is the definition.
(I've seen this in another clue)
'heron in distress' is the wordplay.
'in distress' indicates anagramming the letters.
'heron' with letters rearranged gives 'RHONE'.
(Other definitions for rhone that I've seen before include "River of Switzerland and France" , "River running through France to the Med" , "European river and glacier" , "Fr. river and wine" , "River running through the city of Arles" .)