What does the cryptic crossword clue "David covets ale when drunk - he likes stirring it (6,8)" mean?

The wordplay uses an anagram. anagram of DAVID + COVETS + ALE = DEVILSADVOCATE The answer is DEVILSADVOCATE.

David covets ale when drunk - he likes stirring it (6,8)

Daily Mail Cryptic #16233 | 26 Across | 2020-01-21 flower