They're not often miscast in Westerns (7)
I believe the answer is:
lariats
'westerns' is the definition.
Although both the answer and definition are plural nouns, I cannot understand how they can define each other.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for lariats that I've seen before include "Long noosed ropes" , "Animal tethers" , "Lasso ropes" , "Lassos" .)