Try hard; enterprise (9)
I believe the answer is:
endeavour
I believe this is a double definition.
'try hard' is the first definition.
(I've seen this before)
'enterprise' is the second definition.
(synonyms)
(Other definitions for endeavour that I've seen before include "hard work" , "The first handle inspector has" , "Morse" , "Try hard; enterprise" , "First space shuttle to visit the International Space Station" .)