The most common and most likely answer to this crossword clue is the 12 letter word DECOMMISSION
I've seen this crossword clue in The Guardian
D
E
C
O
M
M
I
S
S
I
O
N
Buddy explains!
The straight part
We know that "Withdraw from action" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case withdraw from action = decommission.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 DECOMMISSION mean?
DECOMMISSION verb- To take out of service or to render unusable.
- To remove or revoke a commission.
- To remove or revoke a formal designation.