Silly Cathy, drinking tons, talking lots (6)
I believe the answer is:
'silly cathy drinking tons talking lots' is the definition.
I can't tell whether this defines the answer.
'silly cathy drinking tons' is the wordplay.
'silly' is an anagram indicator.
'drinking' is an insertion indicator.
'tons' becomes 't'.
'cathy' anagrammed gives 'chaty'.
'chaty' placed around 't' is 'CHATTY'.
Can you help me to learn more?
(Other definitions for chatty that I've seen before include "Prone to gossip" , "Loquacious" , "Full of (trivial) conversation" , "Communicative" , "Talkative or garrulous" .)