Ambience of fear reported, a most unsettling precedent (10)
I believe the answer is:
atmosphere
'ambience' is the definition.
(synonyms)
'fear reported a most unsettling precedent' is the wordplay.
I cannot quite see how this works, but
'a' is found in the answer.
an anagram of 'most' is 'tmos' which is within the answer.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for atmosphere that I've seen before include "Air" , "Feel" , "We are always enveloped in this" , "Spirit" , "climate" .)