Charlie having to drink gin? That's nonsense (8)
I believe the answer is:
claptrap
'nonsense' is the definition.
(thesaurus)
'charlie having to drink gin?' is the wordplay.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'having' says to put letters next to each other.
'to drink' becomes 'lap' (lapping is a kind of drinking**).
'gin?' becomes 'trap' (I've seen this in other clues).
'c'+'lap'+'trap'='CLAPTRAP'
'that's' is the link.
(Other definitions for claptrap that I've seen before include "Tripe" , "Meaningless, insincere or pompous talk" , "Bull" , "Cobblers" , "Utter rubbish" .)