The most common and most likely answer to this crossword clue is the 6 letter word GRADES
G
R
A
D
E
S
Buddy explains!
The straight part
We know that "classes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case classes = grades.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 GRADES mean?
GRADES noun- A rating.
- The performance of an individual or group on an examination or test, expressed by a number, letter, or other symbol; a score.
- A degree or level of something; a position within a scale; a degree of quality.
- A slope (up or down) of a roadway or other passage
- A level of primary and secondary education.
- A student of a particular grade (used with the grade level).
- An area that has been flattened by a grader (construction machine).
- The level of the ground.
- A gradian.
- In a linear system of divisors on an n-dimensional variety, the number of free intersection points of n generic divisors.
- A harsh scraping or cutting; a grating.
- A taxon united by a level of morphological or physiological complexity that is not a clade.
- The degree of malignity of a tumor expressed on a scale.
- To assign scores to the components of an academic test.
- To assign a score to overall academic performance.
- To organize in grades.
- To flatten, level, or smooth a large surface.
- To remove or trim part of a seam allowance from a finished seam so as to reduce bulk and make the finished piece more even when turned right side out.
- To pass imperceptibly from one grade into another.
- Grammar school, primary school, or the years of school prior to high school.