Domestic fowls (7)
'domestic fowls' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for poultry that I've seen before include "Domestic fowls as food source" , "Hens, ducks, etc." , "'Chickens and ducks, say (7)'" , "Domestic fowl" .)
'domestic fowls' is the definition.
(hen is a kind of domestic fowl)
This is the entire clue.
(Other definitions for hens that I've seen before include "Adult chickens" , "Female fowl" , "Poultry" , "Female birds" , "Birds kept for laying" .)