The most common and most likely answer to this crossword clue is the 7 letter word FATIGUE
I've seen this crossword clue in Financial Times
F
A
T
I
G
U
E
More clues leading to the result FATIGUE
- Weary and greasy, I assume ship has to leave
- Right out of shape having scoffed at task
- Weary lot devours half a reptile
- Tire of guitar not entirely cast in iron
- The weariness of military punishment
- Blubber over half of visitors arriving after one is weary
- Weary of large portions of piggy used regularly
- Wash out most of military clothing
- Overweight guide lost, out of depth and weary
- Drain that’s essential to sniff at, I guess
Buddy explains!

The straight part
We know that "The weariness/military punishment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the weariness/military punishment = fatigue.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 FATIGUE mean?
FATIGUE noun- A weariness caused by exertion; exhaustion.
- (often in the plural) A menial task or tasks, especially in the military.
- Material failure, such as cracking or separation, caused by stress on the material.
- To tire or make weary by physical or mental exertion
- To wilt a salad by dressing or tossing it
- To lose so much strength or energy that one becomes tired, weary, feeble or exhausted
- (of a material specimen) to undergo the process of fatigue; to fail as a result of fatigue.