Some mess I spill, ending up ... (8)
I believe the answer is:
ellipsis
'some mess i spill ending up' is the definition.
I can't judge whether this definition defines the answer.
'some mess i spill ending up' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'sispille' can be found hidden inside 'mess i spill ending'.
'sispille' backwards is 'ELLIPSIS'.
Can you help me to learn more?
(Other definitions for ellipsis that I've seen before include "Omission of words from speech or writing" , "Omission of words (gram.)" , "dotty row" , "Omission of parts of words or sentences" , "Set of three dots in a text indicating an omission" .)