The most common and most likely answer to this crossword clue is the 7 letter word AMPUTEE
I've seen this crossword clue in The Guardian
A
M
P
U
T
E
E
More clues leading to the result AMPUTEE
- One has lost a member
- In retreat to meet up: majority of one, missing a member
- Morning place with limitless beer? I may be legless
- Lying back, feet up, magistrate detains Pistorius as example
- Mixed up English team, one short of members?
- Mate up at sea close to gunwale for Nelson, perhaps
- Even curtseyed before a dignitary — one’s lost a member
- He could be disarmed
- Turning feet up, man shows he has lost a toe, unfortunately
- A short encounter took place, one lost a member
Buddy explains!

The straight part
We know that "one, missing a member" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one, missing a member = amputee.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 AMPUTEE mean?
AMPUTEE noun- A person who has had one or more limbs removed.