Weakness of vision in Spain agreed with court (9)
I believe the answer is:
eyestrain
'weakness of vision' is the definition.
'eyestrain' can be an answer for 'weakness' (thesaurus). I am not certain of the 'of vision' bit.
'spain agreed with court' is the wordplay.
'spain' becomes 'e' (abbreviation for Espana).
'agreed' becomes 'yes' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'court' becomes 'train' (I can't justify this - if you can you should give a lot more credence to this answer).
'e'+'yes'+'train'='EYESTRAIN'
'in' is the link.
Can you help me to learn more?
(Other definitions for eyestrain that I've seen before include "this could require attention from ophthalmologist" , "which makes it hard to see" , "tiredness of pupils" , "pupils are involved in such trouble" , "Reader's issue" .)