Period of pageantry (3)
I believe the answer is:
age
'period' is the definition.
(age is a kind of period)
'of pageantry' is the wordplay.
'of' says the answer is hidden in the clue.
'AGE' is hidden within 'pageantry'.
(Other definitions for age that I've seen before include "Time in years" , "Period of time" , "Long period" , "Era; grow old" , "Years since birth" .)