Phrase tome represented gives prevailing mood (10)
I believe the answer is:
atmosphere
'prevailing mood' is the definition.
(I've seen this before)
'phrase tome represented' is the wordplay.
'represented' indicates anagramming the letters.
'phrase'+'tome'='phrasetome'
'phrasetome' anagrammed gives 'ATMOSPHERE'.
'gives' acts as a link.
(Other definitions for atmosphere that I've seen before include "Feeling" , "We are always enveloped in this" , "prevailing mood" , "character" , "Pervading tone or mood" .)