Green; jejune (5)
I believe the answer is:
naive
I believe this clue is a double definition.
'green' is the first definition.
(green can mean naive or innocent)
'jejune' is the second definition.
(I've seen this before)
(Other definitions for naive that I've seen before include "Lacking judgment" , "Showing lack of maturity or judgement" , "Inexperienced and guileless" , "Too simple and trusting" , "Callow" .)