Wild bull left quickly outside at maximum volume (4,5)

'outside at maximum volume' is the definition.
I know nothing about this answer so I can't tell whether this works.

'wild bull left quickly' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'bull' is 'ullb' which is located in the answer.
'left' could be 'l' (common abbreviation) and 'l' is located in the answer.
'quickly' could be 'fast' (synonyms) and 'fast' is present in the leftover letters.
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?