Wet behind the ears
I believe the answer is:
naive
'wet behind the ears' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for naive that I've seen before include "Ingenuous and credulous" , "Excessively trusting or innocent" , "Showing lack of experience or sophistication" , "Too trusting and impractical" , "Unsophisticated and gullible" .)