The most common and most likely answer to this crossword clue is the 5 letter word SIEGE
I've seen this crossword clue in The Daily Telegraph
S
I
E
G
E
More clues leading to the result SIEGE
- See GI shot in wartime event
- It may finally be raised, say — in seconds, that is
- Encirclement, say, if enemy gets energetic at outset
- Investment is, in recession, regularly meagre
- Blockade, for instance, European is backing
- Blockade is over, say, by end of June
- Blockade, for example, is about to surround Spain
- Investment by army is over, say, at end of June
- Kit that’s sillier yet working without batteries
- Military action, say, is about capturing enemy primarily
Buddy explains!

The straight part
We know that "batteries" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case batteries = siege.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 SIEGE mean?
SIEGE noun- (heading) Military action.
- (heading) A seat.
- A place with a toilet seat: an outhouse; a lavatory.
- To assault a blockade of a city or fortress with the intent of conquering by force or attrition; to besiege.