Written symbol proves an 'indrance to itself? (9)
I believe the answer is:
ampersand
'written symbol' is the definition.
(ampersand is a kind of written symbol)
'an 'indrance to itself?' is the wordplay.
I cannot quite understand how this works, but
'an' could be 'per' (synonymous as in 'once an hour', 'once per hour') and 'per' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'proves' is the link.
Can you help me to learn more?
(Other definitions for ampersand that I've seen before include "Plus sign" , "character (sharing with 7)" , "Pens drama using &" , "Symbol for 'and'" , "Union character" .)