Introduction concluded with true style (8)
I believe the answer is:
overture
'introduction' is the definition.
(I have seen 'Musical introduction ' mean 'overture' so perhaps 'introduction' could also mean 'overture')
'concluded with true style' is the wordplay.
'concluded' becomes 'over' (synonyms).
'with' says to put letters next to each other.
'style' indicates an anagram (style can mean to shape or design).
'true' is an anagram of 'ture'.
'over'+'ture'='OVERTURE'
(Other definitions for overture that I've seen before include "Introductory music" , "Opening music" , "Tentative approach" , "Orchestral composition as prelude, or a friendly advance" , "Item of music" .)