Green local is dropping temperature (5)
I believe the answer is:
naive
'green' is the definition.
(green can mean naive or innocent)
'local is dropping temperature' is the wordplay.
'local' becomes 'native' (relating to a particular area).
'is dropping' is a deletion indicator.
'temperature' becomes 't' (abbreviation).
'native' with 't' taken out is 'NAIVE'.
(Other definitions for naive that I've seen before include "Simple and guileless" , "Ingenuous and gullible" , "Lacking guile" , "Innocent or not worldly enough" , "Unaffected; credulous" .)