Watch cutter swing (6)
I believe the answer is:
seesaw
'swing' is the definition.
(I know that seesaw is a type of swing)
'watch cutter' is the wordplay.
'watch' becomes 'see' (see can mean to view or watch).
'cutter' becomes 'saw' (I've seen this in other clues).
'see'+'saw'='SEESAW'
(Other definitions for seesaw that I've seen before include "vacillate in policy" , "Child's game with plank on barrel" , "Playground equipment for kids" , "swing" , "Pivoted amusement" .)