Source of foul language absorbs American flier (8)
I believe the answer is:
flamingo
'flier' is the definition.
(flamingo is a kind of birdanimal)
'source of foul language absorbs american' is the wordplay.
'source of' says to take the initial letters.
'language' becomes 'lingo' (lingo is a kind of language**).
'absorbs' indicates putting letters inside.
'american' becomes 'am' (abbreviation in some contexts).
The initial letter of 'foul' is 'f'.
'lingo' going around 'am' is 'lamingo'.
'f'+'lamingo'='FLAMINGO'
(Other definitions for flamingo that I've seen before include "Wading bird with pink and red plumage" , "Long-legged bird" , "Pretty bird" , "Tall wading bird" , "Exotic bird" .)