The most common and most likely answer to this crossword clue is the 9 letter word ANCHORMEN
I've seen this crossword clue in The Guardian
A
N
C
H
O
R
M
E
N
Buddy explains!
The straight part
We know that "Those running last" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case those running last = anchormen.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 ANCHORMEN mean?
ANCHORMEN noun- The main host of a television or radio program, particularly one relating to the broadcast of news.
- The most reliable runner in a relay team, usually the one that runs last.
- The person on a ship in charge of the anchor.