Disturbed hormone making one grouse (7)
I believe the answer is:
moorhen
'one grouse' is the definition.
(moorhen is a kind of grouse)
'disturbed hormone' is the wordplay.
'disturbed' is an anagram indicator.
'hormone' anagrammed gives 'MOORHEN'.
'making' acts as a link.
(Other definitions for moorhen that I've seen before include "Female red grouse or waterfowl" , "Black waterbird" , "Water bird" , "Medium-sized, blackish aquatic bird with long toes" , "pond bird" .)