Single act performed inside that's extremely volatile (6)
I believe the answer is:
octane
'extremely volatile' is the definition.
I can't tell whether this definition defines the answer.
'single act performed inside' is the wordplay.
'single' becomes 'one' (a single thing - only one).
'performed' is an anagram indicator.
'inside' indicates putting letters inside.
'act' anagrammed gives 'cta'.
'one' enclosing 'cta' is 'OCTANE'.
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for octane that I've seen before include "A liquid hydrocarbon found in petroleum" , "Hydrocarbon found in petrol - at once (anag)" , "Petrol quality rating" , "chemical" , "Fuel component in McLaren vehicle" .)