The most common and most likely answer to this crossword clue is the 8 letter word VERTEBRA
I've seen this crossword clue in The Daily Telegraph
V
E
R
T
E
B
R
A
More clues leading to the result VERTEBRA
- Plunge finally breaking Green supporter’s backbone, partly
- Bone half upright on bare ground
- Contribution to a column: “Evert played with support”
- Irish broadcaster in brave broadcast, showing some backbone
- Outside bet backing King’s Lynn? That shows some backbone
- Note, in part of speech, artist showing bit of backbone
- Green initiative’s ultimate supporter getting item in a column
- Back supporter, green energy supporter
- Clergyman’s up on time, and cooking bare bone
- Green supporter, conserving energy, showing bit of backbone?
Buddy explains!
The straight part
We know that "essential to staying upright" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case essential to staying upright = vertebra.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 VERTEBRA mean?
VERTEBRA noun- Any of the small bones which make up the backbone.