The most common and most likely answer to this crossword clue is the 7 letter word BUGLING
I've seen this crossword clue in The Times
B
U
G
L
I
N
G
Buddy explains!
The straight part
We know that "making the last post" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case making the last post = bugling.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 BUGLING mean?
BUGLING verb- To announce, sing, or cry in the manner of a musical bugle
- The act of playing a bugle.