Australia working with Spain to produce gas (5)
I believe the answer is:
ozone
'gas' is the definition.
(I've seen this before)
'australia working with spain' is the wordplay.
'australia' becomes 'oz'.
'working' becomes 'on'.
'with' means one lot of letters go next to another.
'spain' becomes 'e' (abbreviation for Espana).
'oz'+'on'+'e'='OZONE'
'to produce' acts as a link.
(Other definitions for ozone that I've seen before include "Pungent form of oxygen" , "Bracing air (colloq.)" , "Atmospheric gas shielding us from ultraviolet radiation" , "Allotropic gas" , "Gas; bracing sea air" .)