A coin - the tossing is not determined (8)
I believe the answer is:
inchoate
'not determined' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives occasionally define each other.
'a coin the tossing' is the wordplay.
'tossing' is an anagram indicator.
'a'+'coin'+'the'='acointhe'
'acointhe' anagrammed gives 'INCHOATE'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for inchoate that I've seen before include "Just begun, not yet fully developed" , "Rough" , "Imperfectly formed" , "Immature" , "Undeveloped" .)