Teeter-totter (6)
I believe the answer is:
seesaw
This clue is a double definition.
'teeter' is the first definition.
(I know that teeter can be written as seesaw)
'totter' is the second definition.
(I know that totter can be written as seesaw)
(Other definitions for seesaw that I've seen before include "youngsters' game" , "keep alternating" , "Fluctuate" , "Up-and-down children's game with plank on barrel" , "wild mare" .)