The most common and most likely answer to this crossword clue is the 13 letter word RUBBERNECKING
I've seen this crossword clue in Independent
R
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Buddy explains!
The straight part
We know that "Gaping like a tourist" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gaping like a tourist = rubbernecking.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RUBBERNECKING mean?
RUBBERNECKING verb- To watch by craning the neck (as though it were made of rubber), especially if the observer and observed are in motion relative to each other.
- The act of slowing down whilst driving a vehicle, in order to see the scene of an accident.
- Generally, any act of observation in a manner considered unduly overt or otherwise unseemly.