Criticised youngster getting dates mixed up (9)
I believe the answer is:
lambasted
'criticised' is the definition.
(lambasting is a kind of criticising)
'youngster getting dates mixed up' is the wordplay.
'youngster' becomes 'lamb' (a lamb is a young sheep).
'getting' is a charade indicator (letters next to each other).
'mixed up' is an anagram indicator.
'dates' anagrammed gives 'asted'.
'lamb'+'asted'='LAMBASTED'
(Other definitions for lambasted that I've seen before include "Tore strips off" , "Thrashed" , "Censured severely or angrily" , "Made blast (anag) - reprimanded" , "Roasted" .)