Play (with) (7)
I believe the answer is:
twiddle
'play with' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for twiddle that I've seen before include "Adjust" , "Play with and twist around" , "Idly rotate (one's thumbs?)" , "Jiggle" , "Twirl (thumbs?)" .)