Testing toy Turing designed (6,3)
I believe the answer is:
trying out
'testing' is the definition.
('try out' can be a synonym of 'test')
'toy turing designed' is the wordplay.
'designed' indicates an anagram (designed with the letters).
'toy'+'turing'='toyturing'
'toyturing' with letters rearranged gives 'TRYING OUT'.
(Other definitions for trying out that I've seen before include "Experimenting with" , "sampling" .)