Tom's angina produced by bad blood (10)
I believe the answer is:
antagonism
'bad blood' is the definition.
(thesaurus)
'tom's angina produced' is the wordplay.
'produced' indicates an anagram.
'toms'+'angina'='tomsangina'
'tomsangina' with letters rearranged gives 'ANTAGONISM'.
'by' is the link.
(Other definitions for antagonism that I've seen before include "Active opposition" , "Active hostility" .)