The most common and most likely answer to this crossword clue is the 8 plus 7 letter word NATIONAL SERVICE
I've seen this crossword clue in The Guardian
N
A
T
I
O
N
A
L
S
E
R
V
I
C
E
More clues leading to the result NATIONAL SERVICE
- State funeral? Participation in it is no longer required
- Alien contrives to secure a spell in the military
- Flying alien contrives to secure a spell in the army?
- Ancestor in a live re-enactment of compulsory time in the military
- Inaction reveals varied activity abandoned in UK
- Moving on can revitalise conscription
- Disabled Iris cannot leave for draft
Buddy explains!
The straight part
We know that "compulsory time in the military" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case compulsory time in the military = national service.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.