Bird, female swan, arm hugging one (7)
I believe the answer is:
penguin
'bird' is the definition.
(penguin is a kind of bird)
'female swan arm hugging one' is the wordplay.
'female swan' becomes 'pen' (I've seen this before).
'arm' becomes 'gun' (gun is a kind of arm).
'hugging' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'gun' placed around 'i' is 'guin'.
'pen'+'guin'='PENGUIN'
(Other definitions for penguin that I've seen before include "Flightless sea bird" , "Black-and-white antarctic bird" , "Flightless marine bird" , "Antarctic seabird with flippers for wings" , "Chocolate biscuit" .)