Stumbling blocks set against cataracts (8)
I believe the answer is:
pitfalls
'stumbling blocks' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Maybe there's an association between them I don't understand?
'set against cataracts' is the wordplay.
'set against' becomes 'pit' (I can't explain this - if you can you should believe this answer much more).
'cataracts' becomes 'falls' (I've seen this in another clue).
'pit'+'falls'='PITFALLS'
Can you help me to learn more?
(Other definitions for pitfalls that I've seen before include "Hidden dangers, booby traps." , "Unsuspected dangers or difficulties - for miners?" , "Lifts pal from unexpected difficulties or dangers" , "Catches" .)