A joke, maybe, but it’s old material (3)
I believe the answer is:
rag
This might be a double definition.
'a joke' is the first definition.
(rag is a kind of joke)
'it's old material' is the second definition.
'maybe but' is the link.
I am not very happy about this link. Some or all of it may belong to one of the definitions.
Can you help me to learn more?
(Other definitions for rag that I've seen before include "Cloth for wiping" , "students' excuse to misbehave?" , "Scrap; one lost by the angry" , "Duster, perhaps" , "Student event" .)