The most common and most likely answer to this crossword clue is the 12 letter word INVERTEBRATE
I've seen this crossword clue in The Guardian
I
N
V
E
R
T
E
B
R
A
T
E
Buddy explains!

The straight part
We know that "Spineless type" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spineless type = invertebrate.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 INVERTEBRATE mean?
INVERTEBRATE noun- An animal without vertebrae, i.e. backbone.
- A spineless person; a coward.
- Lacking a backbone.