Go after toys, principally to play with (7)
I believe the answer is:
'play with' is the definition.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for twiddle that I've seen before include "Jiggle" , "Twirl (thumbs?)" , "Finger idly" , "Play nervously (with something)" , "Turn in a purposeless way" .)