School lied about playground item (5)
I believe the answer is:
slide
'playground item' is the definition.
(I've seen this before)
'school lied about' is the wordplay.
'school' becomes 's' (**).
'about' is an anagram indicator.
'lied' is an anagram of 'lide'.
's'+'lide'='SLIDE'
(Other definitions for slide that I've seen before include "Slip, slither, skid" , "Playground chute" , "Decline" , "Transparency" , "Playground item" .)