Argument on premises burst gym's lilos (9)
I believe the answer is:
syllogism
'argument on premises' is the definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Maybe there's an association between them I don't understand?
'burst gym's lilos' is the wordplay.
'burst' indicates an anagram.
'gyms'+'lilos'='gymslilos'
'gymslilos' is an anagram of 'SYLLOGISM'.
Can you help me to learn more?
(Another definition for syllogism that I've seen is " Deductive reasoning".)