Sorrel seems strangely savage (11)
I believe the answer is:
remorseless
'savage' is the definition.
(I've seen this before)
'sorrel seems strangely' is the wordplay.
'strangely' indicates an anagram.
'sorrel'+'seems'='sorrelseems'
'sorrelseems' anagrammed gives 'REMORSELESS'.
(Other definitions for remorseless that I've seen before include "Not letting up," , "Savage" , "Relentless" , "Inhumane" , "Unmerciful" .)