Risk associated ultimately with negative emotion (6)
I believe the answer is:
danger
'risk' is the definition.
(synonyms)
'associated ultimately with negative emotion' is the wordplay.
'ultimately' indicates one should take the final letters.
'with' is a charade indicator (letters next to each other).
'negative emotion' becomes 'anger'.
The last letter of 'associated' is 'd'.
'd'+'anger'='DANGER'
(Other definitions for danger that I've seen before include "Ranged about in some peril" , "Undesirable possibility" , "'Peril, risk (6)'" , "Peril, exposure to harm" , "Peril in garde" .)