This month incorporated opening of the faculty (8)
I believe the answer is:
instinct
'faculty' is the definition.
(thesaurus)
'this month incorporated opening of the' is the wordplay.
'this month' becomes 'inst' (I've seen this before).
'incorporated' becomes 'inc'.
'opening of' suggests taking the first letters.
The first letter of 'the' is 't'.
'inst'+'inc'+'t'='INSTINCT'
(Other definitions for instinct that I've seen before include "Innate reaction" , "Basic natural drive" , "Inborn impulse or tendency 8)" , "Ability" , "Gut reaction, impulse" .)