Twice, topped cask with a little light which has quite a long name (6-9)

'twice topped cask with a little light which has quite a long name' is the definition.
I can't tell whether this definition defines the answer.

'twice topped cask with a little light which has quite a long name' is the wordplay.
I cannot quite understand how this works, but
'twice' could be 'double' (synonyms) and 'double' is present in the answer.
'cask' could be 'barrel' (synonyms) and 'barrel' is present in the answer.
'little' could be 'l' (abbreviation) and 'l' is located in the answer.
'name' could be 'ed' (short for Edward) and 'ed' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?