Old writing implement (5)
(Other definitions for quill that I've seen before include "Feather for writing" , "Pen made from a feather" , "Old pen" , "Old writer" , "Hollow part of feather" .)
'old writing implement' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stylus that I've seen before include "Needle used for playing gramophone records" , "One going on record" , "Kind of needle for playing record" , "Pointed device on a record player" , "Old writing implement" .)