Frankfurter in a bun (6)
'frankfurter in a bun' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for hot dog that I've seen before include "Item of fast food" , "Sausage snack" , "One panting" , "Sausage in a bun" , "grub?" .)
(Other definitions for hotdog that I've seen before include "junk food" , "Food served at arena" , "snack" .)