Rascals splitting least colourful historic document (10)
I believe the answer is:
palimpsest
'document' is the definition.
(I have seen 'recycled document' mean 'palimpsest' so perhaps 'document' could also mean 'palimpsest')
'rascals splitting least colourful historic' is the wordplay.
I cannot really see how this works, but
'rascals' could be 'imps' ('imp' can be a synonym of 'rascal') and 'imps' is found within the answer.
an anagram of 'least' is 'alest' which is present in the remaining letters.
A single letter 'p' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for palimpsest that I've seen before include "recycled document" , "Recycled manuscript" , "Reused parchment" , "Simple taps (anag.); a manuscript" .)