Prepared to be heavily criticised, drinking litres (7)
I believe the answer is:
planned
'prepared' is the definition.
(thesaurus)
'heavily criticised drinking litres' is the wordplay.
'heavily criticised' becomes 'panned' (to pan is to criticise heavily).
'drinking' means one lot of letters goes inside another.
'litres' becomes 'L' (abbreviation).
'panned' going around 'l' is 'PLANNED'.
'to be' is the link.
(Other definitions for planned that I've seen before include "Designed, plotted" , "Devised" , "Intended or designed" , "Prepared carefully in advance" , "Arranged in advance" .)