Magnificent concert's finale due to include Queen (8)
I believe the answer is:
towering
'magnificent' is the definition.
(I've seen this before)
'concert's finale due to include queen' is the wordplay.
'finale' suggests the final letters.
'due to' becomes 'owing' (owing money).
'include' means one lot of letters goes inside another.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
The last letter of 'concert' is 't'.
'owing' placed around 'er' is 'owering'.
't'+'owering'='TOWERING'
(Other definitions for towering that I've seen before include "Grew into (anag.)" , "Very intense (rage)" , "Very tall" , "I get worn (anag)" , "Magnificent" .)