The most common and most likely answer to this crossword clue is the 10 letter word PROTRACTED
I've seen this crossword clue in The Guardian
P
R
O
T
R
A
C
T
E
D
Buddy explains!
The straight part
We know that "overlong" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case overlong = protracted.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 PROTRACTED mean?
PROTRACTED verb- To draw out; to extend, especially in duration.
- To use a protractor.
- To draw to a scale; to lay down the lines and angles of, with scale and protractor; to plot.
- To put off to a distant time; to delay; to defer.
- To extend; to protrude.
- Lasting for a long time or longer than expected or usual.