Has a turn in end maintaining grave (9)
I believe the answer is:
saturnine
'grave' is the definition.
(saturnine can mean grave or serious)
'has a turn in end maintaining' is the wordplay.
'maintaining' indicates a hidden word (the solution is held or maintained within the clue).
'SATURNINE' is hidden within 'has a turn in end'.
(Other definitions for saturnine that I've seen before include "dull" , "A rust nine chnage to be grave and gloomy" , "moody" , "dismal" , "Turn in sea makes one gloomy" .)