Bracing air a specified person associated with Australia (5)
I believe the answer is:
ozone
'bracing air' is the definition.
(I've seen this before)
'a specified person associated with australia' is the wordplay.
'a specified person' becomes 'one' ('one' can mean an unspecified person. I am not sure about the 'specified' bit.).
'associated with' means one lot of letters go next to another.
'australia' becomes 'oz' (informal name for Australia).
'one' after 'oz' is 'OZONE'.
Can you help me to learn more?
(Other definitions for ozone that I've seen before include "Gas forming protective layer" , "Trioxygen" , "Form of oxygen in earth's upper atmosphere - there's a hole in it" , "By sea, you could take in this" , "Toxic form of oxygen" .)