Offspring, it's said, turned to drink (6)
I believe the answer is:
brewed
'turned to drink' is the definition.
(to brew is to create a drink)
'offspring it's said' is the wordplay.
'offspring' becomes 'brood' (I've seen this before).
'it's said' shows a homophone (sound like).
'brood' sounds like 'BREWED'.
(Other definitions for brewed that I've seen before include "Fermented" , "Made tea or beer" , "make beer" , "ready to get drunk?" , "Made by boiling and fermentation, say beer" .)