Old man, unusually spry, snatching University manuscript from long ago (7)
I believe the answer is:
papyrus
'manuscript from long ago' is the definition.
(ancient writing material)
'old man unusually spry snatching university' is the wordplay.
'old man' becomes 'pa' (both can mean father).
'unusually' is an anagram indicator.
'snatching' is an insertion indicator.
'university' becomes 'u' (abbreviation for university).
'spry' is an anagram of 'pyrs'.
'pyrs' enclosing 'u' is 'pyrus'.
'pa'+'pyrus'='PAPYRUS'
(Other definitions for papyrus that I've seen before include "Writing material used by ancient Egyptians" , "Kind of paper used in old Egyptian manuscripts" , "Ancient paper plant" , "Paper made from reed by ancient Egyptians" , "Egyptian paper reed" .)