Upset ram running amok against the current (8)
I believe the answer is:
upstream
'against the current' is the definition.
(synonyms)
'upset ram running amok' is the wordplay.
'running amok' indicates anagramming the letters.
'upset'+'ram'='upsetram'
'upsetram' is an anagram of 'UPSTREAM'.
(Other definitions for upstream that I've seen before include "Against a river's natural flow" , "Current trend is not" , "Towards (river's) source" , "Going back to the source" , "contraflow" .)