Test or put to experimental use (3,3)
I believe the answer is:
try out
I believe this is a double definition.
'test' is the first definition.
(try out can mean to test or trial)
'put to experimental use' is the second definition.
(I've seen this before)
(Other definitions for try out that I've seen before include "Sample" , "Taste" , "Test and evaluate" , "Put to experimental use" .)