The most common and most likely answer to this crossword clue is the 6 letter word BERTHA
I've seen this crossword clue in The Times
B
E
R
T
H
A
More clues leading to the result BERTHA
- Sleeping accommodation needed by a woman
- Big gun given position in Albert Hall
- Woman's bad breath
- On bed find a collar
- Bed a woman
- Big German gun beginning to blast earth to pieces
- Somewhere to sleep with a girl
- Woman in bed with touch of arthritis
- Shooter with bad breath
- Only some remember that old lace collar
Buddy explains!

The straight part
We know that "Big gun" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case big gun = bertha.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 BERTHA mean?
BERTHA noun- A lace collar that covers the shoulders of a dress