Clue: Something online for minors, I say, drinking liquor (4-4)
Answer: CHOO CHOO
Explanation: Definition: Something online for minors
definition: a train is something that runs "on [a railway] line", and might be called CHOO CHOO by children/"minors"
 **COO**=exclamation of surprise="I say"; around **HOOCH**="liquor"