Show time — long to be outside (7)
I believe the answer is:
pageant
'show' is the definition.
(I've seen this before)
'time long to be outside' is the wordplay.
'time' becomes 'age' (an age is a period of time).
'long' becomes 'pant' (I've seen this before).
'to be outside' is an insertion indicator.
'age' put within 'pant' is 'PAGEANT'.
(Other definitions for pageant that I've seen before include "Elaborate procession on historical theme" , "Colourful display or parade" , "elaborate display" , "Series of tableaux etc" , "Parade with tableaux" .)