Clue: Getting souvenir from Gatwick's terminal: go back with Japanese drink (8)
Answer: KEEPSAKE
Explanation: Definition: souvenir
"Getting… from…" connects the definition to the rest of the clue, rather than adding to the rest of the wordplay
 
the end letter/"terminal" of [Gatwic]-**K **+ **PEE**="go" reversed/"back" + **SAKE**="Japanese drink"