Beery in-law’s drunk strong ale (6,4)
I believe the answer is:
barley wine
'strong ale' is the definition.
(I've seen this in another clue)
'beery in-law's drunk' is the wordplay.
'drunk' is an anagram indicator.
'beery'+'in'+'law'='beeryinlaw'
'beeryinlaw' anagrammed gives 'BARLEY WINE'.
(Other definitions for barley wine that I've seen before include "ale" , "cereal product" , "beer" .)