The most common and most likely answer to this crossword clue is the 7 letter word RAGGING
I've seen this crossword clue in The Sunday Telegraph
R
A
G
G
I
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G
Buddy explains!

The straight part
We know that "teasing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case teasing = ragging.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 RAGGING mean?
RAGGING verb- To decorate (a wall, etc.) by applying paint with a rag.
- To become tattered.
- To break (ore) into lumps for sorting.
- To cut or dress roughly, as a grindstone.
- To scold or tell off; to torment; to banter.
- To drive a car or another vehicle in a hard, fast or unsympathetic manner.
- To tease or torment, especially at a university; to bully, to haze.
- To play or compose (a piece, melody, etc.) in syncopated time.
- To dance to ragtime music.
- To add syncopation (to a tune) and thereby make it appropriate for a ragtime song.
- The act of one who rags or teases.
- An initiation in educational institutions (e.g. universities) usually involving harassment by upperclassmen.