Go up and down (2-2)
'go up and down' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for seesaw that I've seen before include "Rise and fall" , "Piece of playground equipment" , "Plaything with up-and-down movement" , "Change back and forth rapidly and repeatedly" , "keep alternating" .)
This clue is a double definition.
'go' is the first definition.
(both can mean energy or vitality)
'up and down' is the second definition.
(Other definitions for pep that I've seen before include "Ginger; tax-free investment" , "Get-up-and-go" , "savings plan" , "Energy, zip" , "Palindromic energy or vim" .)
'go up and down' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for yo-yo that I've seen before include "Move up and down" , "Toy (with ups-and-downs!)" , "Toy - fluctuate wildly" , "Toy again in fashion" , "Toy consisting of a reel and string" .)
(Other definitions for yoyo that I've seen before include "Toy" , "Item on string" , "Plaything" .)