Casual pyrotechnist no pro and not natural (9)
I believe the answer is:
synthetic
'not natural' is the definition.
(something synthesised is not natural)
'casual pyrotechnist no pro' is the wordplay.
'casual' is an anagram indicator (a casual or disordered version of the letters).
'no' suggests deleting specific letters.
'pyrotechnist' with 'pro' taken out is 'ytechnist'.
'ytechnist' is an anagram of 'SYNTHETIC'.
'and' is the link.
(Other definitions for synthetic that I've seen before include "Artificially made" , "Mock" , "Man-made, not natural" , "Artificially-made compound" , "Man-made (fibre)" .)