Inoffensive group's first to enter country (6)
I believe the answer is:
benign
'inoffensive' is the definition.
(thesaurus)
'group's first to enter country' is the wordplay.
'first' suggests taking the first letters.
'to enter' means one lot of letters goes inside another.
'country' becomes 'benin' (Benin is an example**).
The first letter of 'group' is 'g'.
'g' placed into 'benin' is 'BENIGN'.
(Other definitions for benign that I've seen before include "Harmless or kind" , "Genial, kindly" , "Kindly or non-malignant" , "Mild and gentle, not malignant" , "Liberal" .)