Make out endless rubbish was only stopgap material (5)

I believe the answer is:

oakum

I'm a little stuck... Click here to teach me more about this clue!

'material' is the definition.
(I know that oakum is a material)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for oakum that I've seen before include "Fibrous material from rope" , "What convicts used to pick" , "Rope fibre for caulking wooden ships" , "Tarred rope" , "Fibre from unravelled old rope" .)

I've seen this clue in the Sydney Morning Herald.

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