Ancient document with syrup spread across a page (7)
I believe the answer is:
papyrus
'ancient document' is the definition.
(ancient writing material)
'syrup spread across a page' is the wordplay.
'spread' indicates an anagram.
'across' is an insertion indicator.
'page' becomes 'p'.
'syrup' with letters rearranged gives 'pyrus'.
'a'+'p'='ap'
'pyrus' placed around 'ap' is 'PAPYRUS'.
'with' acts as a link.
(Other definitions for papyrus that I've seen before include "Egyptian writing matter" , "manuscript" , "Egyptian water plant" , "Paper made from reed by ancient Egyptians" , "Writing material used by ancient Egyptians" .)