Inexperienced in setting up hostilities (3)
I believe the answer is:
raw
'inexperienced' is the definition.
(similar in meaning)
'setting up hostilities' is the wordplay.
'setting up' says the letters should be written backwards.
'hostilities' becomes 'war' (hostilities between two nations).
'war' back-to-front is 'RAW'.
'in' is the link.
(Other definitions for raw that I've seen before include "Uncooked or unsophisticated" , "Uncooked or unsavoury" , "Unrefined" , "Not prepared" , "Damp and chilly" .)