Duck in second camp: that is flying off (6)
I believe the answer is:
scoter
'duck' is the definition.
(I know that scoter is a type of sea duck)
'in second camp that is flying off' is the wordplay.
'in second' becomes 's' (common abbreviation. I am not sure about the 'in' bit.).
'camp' becomes 'coterie' (synonyms).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'flying off' is a deletion indicator.
'coterie' with 'ie' taken away is 'coter'.
's'+'coter'='SCOTER'
Can you help me to learn more?
(Other definitions for scoter that I've seen before include "Diving duck with black plumage" , "Sea duck" , "Species of diving duck" , "Duck - escort (anag)" , "Large duck -- corset (anag)" .)