The most common and most likely answer to this crossword clue is the 8 letter word OVERLAPS
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More clues leading to the result OVERLAPS
Buddy explains!

The straight part
We know that "Coincides with" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case coincides with = overlaps.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 OVERLAPS mean?
OVERLAPS noun- Something that overlaps or is overlapped
- A situation in the game where an attacking line has more players in it than the defensive line coming to meet it. The attacking side may exploit the overlap by using their superior numbers to break the opposition's defensive line. If attackers outnumber defenders by more than one player this is often termed a two man overlap or three man overlap, etc. If the attacking side fails to break through usually due to poor execution, they are said to waste an overlap.
- The payment of a spouse's or other dependant's annuity benefits concurrently with the member's benefits, on death of the member during the guarantee period.