The most common and most likely answer to this crossword clue is the 4 plus 5 letter word HOME GUARD
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More clues leading to the result HOME GUARD
- Walmington-on-Sea’s finest in Minder?
- Criminal made rough arrangement for defence
- 15 and his TV platoon roughed ma about?
- Pike this old defence force employed
- Volunteers love joining compiler in timeless cask ale round
- Defensive group made rough manoeuvres
- Made rough distribution of volunteer force
- Volunteer troops made rough manoeuvres
Buddy explains!

The straight part
We know that "old defence force" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old defence force = home guard.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.