The most common and most likely answer to this crossword clue is the 6 letter word LESSEN
I've seen this crossword clue in Financial Times
L
E
S
S
E
N
More clues leading to the result LESSEN
- Drop class by the sound of it
- Lower school period for dictation?
- Large German city shrink
- Speaker’s moral decline
- “Make a reduction in class”, we’re told
- Drop something learned aurally
- In Wales, sensational shrink
- Mitigate rebuke, say?
- Drop first of leaflets on German city
- Reduce length of class given by lecturer
Buddy explains!

The straight part
We know that "Drop" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case drop = lessen.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 LESSEN mean?
LESSEN verb- To make less; to diminish; to reduce.
- To become less.