Spectacle to make one gasp about period of history (7)
I believe the answer is:
pageant
'spectacle' is the definition.
(I've seen this before)
'one gasp about period of history' is the wordplay.
'one gasp' becomes 'pant' (synonyms).
'about' is an insertion indicator.
'period of history' becomes 'age' (I've seen this before).
'pant' going around 'age' is 'PAGEANT'.
'to make' acts as a link.
(Other definitions for pageant that I've seen before include "Dramatic performance" , "Splendid procession, parade" , "Costumed procession" , "Magnificent parade" , "Make public spectacle" .)