Innocent Ivan goes out East (5)
I believe the answer is:
naive
'innocent' is the definition.
(similar in meaning)
'ivan goes out east' is the wordplay.
'goes out' indicates anagramming the letters.
'east' becomes 'e' (abbreviation).
'ivan' anagrammed gives 'naiv'.
'naiv'+'e'='NAIVE'
(Other definitions for naive that I've seen before include "Natural, unaffected" , "Ingenuous and credulous" , "Short on experience" , "Ingenuous, easily deceived" , "Wet behind ears" .)