Shades grass area where vision obscured (5,4)
I believe the answer is:
'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).
Can you help me to learn more?
(Other definitions for blind spot that I've seen before include "Area where understanding is lacking or one is unsighted", "where one cannot see", "Hazard for driver", "Unseen area of road", "Area where vision is obstructed".)