The most common and most likely answer to this crossword clue is the 7 letter word NECKING
I've seen this crossword clue in The Times
N
E
C
K
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More clues leading to the result NECKING
Buddy explains!

The straight part
We know that "Drinking/engaging in amorous activity?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case drinking/engaging in amorous activity? = necking.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 NECKING mean?
NECKING verb- To hang by the neck; strangle; kill, eliminate
- To make love; to intently kiss or cuddle; to canoodle.
- To drink rapidly.
- To decrease in diameter.
- A behavior among male giraffes where they hold combat for social dominance using their necks as weapons.
- A neckmould.
- Chugging beer.
- Making out; kissing profusely, especially on the neck.