The most common and most likely answer to this crossword clue is the 6 letter word ALTERS
I've seen this crossword clue in The Daily Telegraph
A
L
T
E
R
S
Buddy explains!
The straight part
We know that "Changes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case changes = alters.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 ALTERS mean?
ALTERS noun- A table or similar flat-topped structure used for religious rites.
- A raised area around an altar in a church; the sanctuary.
- Anything that is worshipped or sacrificed to.
- To change the form or structure of.
- To become different.
- To tailor clothes to make them fit.
- To castrate, neuter or spay (a dog or other animal).
- To affect mentally, as by psychotropic drugs or illness.
- (especially in the plural) An identity or headmate of a person with dissociative identity disorder (previously known as multiple personality disorder).