Quotations from old treatises (8)
I believe the answer is:
extracts
'quotations' is the definition.
(I've seen this before)
'old treatises' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'treatises' becomes 'tracts' (tract is a kind of treatise).
'ex'+'tracts'='EXTRACTS'
'from' acts as a link.
(Other definitions for extracts that I've seen before include "Passages taken from, say, books" , "Removes" , "portions of text" , "quotations" , "Draws out portions of books" .)