This is no way to drink patent medicine (7)
I believe the answer is:
nostrum
'patent medicine' is the definition.
(nostrum is a kind of patent medicine)
'this is no way to drink' is the wordplay.
'this is no' becomes 'no'.
'way' becomes 'st'.
'to drink' becomes 'rum' (I've seen this before**).
'no'+'st'+'rum'='NOSTRUM'
(Other definitions for nostrum that I've seen before include "Quack remedy or pet scheme" , "Patent medicine of highly questionable value" , "Simple, remedy" , "Ineffective medical preparation" , "Quack cure" .)