The safety of the circus performer may depend on this (7)
I believe the answer is:
trapeze
This clue could be a double definition.
'the safety' is the first definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'circus performer may depend on this' is the second definition.
The definition suggests a singular noun which matches the answer.
'of the' acts as a link.
Can you help me to learn more?
(Other definitions for trapeze that I've seen before include "What the daring young man in the circus flies on" , "Circus acrobatsO swing" , "Acrobatic equipment" , "Horizontal bar as swing for acrobats" , "Bar for swinger" .)