Animal hair found in frankfurter (3)
I believe the answer is:
fur
'animal hair' is the definition.
(I know that fur is a type of coat)
'in frankfurter' is the wordplay.
'in' says the answer is hidden in the clue.
'FUR' is hidden within 'frankfurter'.
'found' acts as a link.
(Other definitions for fur that I've seen before include "Animal's coat converted to human use" , "Hard water pipe coating" , "Eg, sable or mink" , "Hairy animal's coat" , "Hairy animal coat" .)