Fun for kids on at playhouse initially is revamped (5)
I believe the answer is:
panto
'fun for kids' is the definition.
(I've seen this before)
'on at playhouse initially is revamped' is the wordplay.
'initially' indicates taking the first letters.
'is revamped' is an anagram indicator.
The initial letter of 'playhouse' is 'p'.
'on'+'at'+'p'='onatp'
'onatp' anagrammed gives 'PANTO'.
(Other definitions for panto that I've seen before include "Slapstick theatre for children (abbr)" , "Cinderella or Puss in Boots, say?" , "Seasonal "he's behind you!" entertainment" , "festive entertainment" , "Trad. Christmas fun (abbr.)" .)