Mercurial little creature biting curly tail (8)
I believe the answer is:
volatile
'mercurial' is the definition.
(I've seen this in another clue)
'little creature biting curly tail' is the wordplay.
I cannot really understand how this works, but
'little' could be 'l' (abbreviation) and 'l' is found within the answer.
an anagram of 'tail' is 'atil' which is within the answer.
The remaining letters 'voe' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for volatile that I've seen before include "A love lit badly could be changeable" , "apt to change" , "Fickle; tending to vaporise" , "Explosive or excitable" , "A live lot being changeable" .)