The most common and most likely answer to this crossword clue is the 3 plus 3 plus 4 letter word FOR THE CHOP
I've seen this crossword clue in The Guardian
F
O
R
T
H
E
C
H
O
P
Buddy explains!
The straight part
We know that "About to get fired" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case about to get fired = for the chop.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.