Makes money, I say, from big containers (4)
I believe the answer is:
urns
'containers' is the definition.
(urn is a kind of container)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for urns that I've seen before include "Large vessels for tea" , "Runs to get large vases" , "Funereal vases" , "Vase-shaped vessels" , "Vessels to hold the ashes of the dead" .)