Bird, duck, with head of indigo, in part (6)
I believe the answer is:
oriole
'bird' is the definition.
(oriole is a kind of bird)
'duck with head of indigo in part' is the wordplay.
'duck' becomes 'o'.
'with' indicates putting letters inside.
'head of' suggests taking the first letters.
'in part' becomes 'role' ('role' can be a synonym of 'part'. I am not sure about the 'in' bit.**).
The first letter of 'indigo' is 'i'.
'i' put inside 'role' is 'riole'.
'o'+'riole'='ORIOLE'
Can you help me to learn more?
(Other definitions for oriole that I've seen before include "Did Leo or I hear the tropical songbird?" , "Baseball player in Baltimore" , "(Tropical or American) songbird" , "Songbird with yellow and black plumage -- Leo or I (anag)" , "Oil ore, strangely, for the songbird" .)