Shades grass area where vision obscured (5,4)
I believe the answer is:
blind spot
'area where vision obscured' is the definition.
I can't tell whether this definition defines the answer.
'shades grass' is the wordplay.
'shades' becomes 'blinds' (I've seen this in another clue).
'grass' becomes 'pot' (cannabis).
'blinds'+'pot'='BLIND SPOT'
Can you help me to learn more?
(Other definitions for blind spot that I've seen before include "Hazard for driver" , "source of misunderstanding?" , "Area where vision is obstructed" , "where one cannot see" , "Area where understanding is lacking or one is unsighted" .)