Morse's first name and last always stated (9)
I believe the answer is:
'morse's first name' is the definition.
(first name of the character Inspector Morse)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for endeavour that I've seen before include "Try to achieve something" , "Aspire; attempt" , "Try hard; enterprise" , "Attempt by employing effort" , "Cook's old vessel" .)