Test shaft on chopper sent back (7)
I believe the answer is:
examine
'test' is the definition.
(I know that test is a kind of examine)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for examine that I've seen before include "Subject to scrutiny" , "research" , "Check" , "Thoroughly inspect" , "Question closely" .)