The most common and most likely answer to this crossword clue is the 6 letter word ARMING
I've seen this crossword clue in The Sunday Telegraph
A
R
M
I
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G
More clues leading to the result ARMING
Buddy explains!
The straight part
We know that "Preparing for combat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case preparing for combat = arming.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 ARMING mean?
ARMING verb- To take by the arm; to take up in one's arms.
- To supply with armour or (later especially) weapons.
- To prepare a tool or a weapon for action; to activate.
- To cover or furnish with a plate, or with whatever will add strength, force, security, or efficiency.
- To furnish with means of defence; to prepare for resistance; to fortify, in a moral sense.
- To take up weapons; to arm oneself.
- To fit (a magnet) with an armature.
- A piece of tallow or soap put in the cavity and over the bottom of a sounding lead to pick up samples of the bottom of the sea.
- The act of supplying with arms and ammunition in preparation of a conflict
- (chiefly in the plural) One of the red dress cloths formerly hung fore and aft outside of a ship's upper works on holidays.