Accessory (5)
'accessory' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for extra that I've seen before include "additional supplies" , "Especially" , "E.g. wide in cricket" , "to boot" , "Bit actor in movie's crowd scenes" .)
'accessory' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for add-on that I've seen before include "Extra charge" , "Accessory device" , "Feature bolted on to a standard model or package" , "Computer peripheral" , "Extra unit, peripheral" .)
'accessory' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for attachment that I've seen before include "Fond regard" , "Affection" , "devotion" , "what often comes with spam?" , "Document with e-mail" .)