Papers from Spain linked to the greatest manuscript reflecting unrealistic pursuit of perfection (8)
I believe the answer is:
idealism
'pursuit of perfection' is the definition.
(I've seen this before)
'papers from spain linked to the greatest manuscript reflecting' is the wordplay.
'papers from spain' becomes 'ide' (I can't explain this - if you can you should give a lot more credence to this answer).
'linked to' is a charade indicator (letters next to each other).
'the greatest' becomes 'ali' (film about Muhammad Ali).
'manuscript' becomes 'ms' ('ms' can be a synonym of 'manuscript').
'reflecting' says the letters should be written in reverse.
'ms' backwards is 'sm'.
'ide'+'ali'+'sm'='IDEALISM'
'unrealistic' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for idealism that I've seen before include "Thoughts of perfection for miladies" , "Pursuit of the perfect" , "Utopian pursuit" , "A view of Berkeley" , "Desire for perfection" .)