A large number request a large storage container (4)

I believe the answer is:

cask

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

'a large storage container' is the definition.
'cask' can be an answer for 'container' (cask is a kind of container). I'm not sure about the 'a large storage' bit.

'a large number request' is the wordplay.
'a large number' becomes 'c' ().
'request' becomes 'ask' (to ask is to request something).
'c'+'ask'='CASK'

Can you help me to learn more?

(Other definitions for cask that I've seen before include "Wine barrel" , "Wine vessel; sack (anag.)" , "Large barrel" , "Keg" , "Beer container" .)

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

Want a hint initially instead of a full solution? Install my app