The most common and most likely answer to this crossword clue is the 7 letter word EPONYMS
E
P
O
N
Y
M
S
Buddy explains!

The straight part
We know that "persons whose names are used to name other places or things" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case persons whose names are used to name other places or things = eponyms.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 EPONYMS mean?
EPONYMS noun- A real or fictitious person's name that has given rise to the name of a particular item.
- A word formed from a real or fictive person’s name.
- (by extension) A word formed from a real or fictive place or thing.