Poor Dave cleaned lav lacking a qualification (8,5)

I believe the answer is:

advanced level

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'qualification' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'poor dave cleaned lav lacking a' is the wordplay.
'poor' indicates an anagram.
'lacking' is a deletion indicator.
'dave'+'cleaned'+'lav'='davecleanedlav'
'davecleanedlav' with 'a' taken out is 'dvecleanedlav'.
'dvecleanedlav' is an anagram of 'ADVANCED LEVEL'.

Can you help me to learn more?

(Other definitions for advanced level that I've seen before include "school exam" , "qualification?" .)

I've seen this clue in The Telegraph.

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