Notice saying "Playground Equipment" (6)
I believe the answer is:
'playground equipment' is the definition.
(I've seen this before)
'notice saying' is the wordplay.
'notice' becomes 'see' (notice can mean to spot or see).
'saying' becomes 'saw' (saw is a kind of saying).
(Other definitions for seesaw that I've seen before include "Playground device" , "wild mare" , "Plaything with up-and-down movement" , "Move up and down on the plaything" , "Rock unsteadily" .)