Adds to suffering in conflict (2,4)
I believe the answer is:
at odds
'in conflict' is the definition.
(I've seen this before)
'adds to suffering' is the wordplay.
'suffering' is an anagram indicator.
'adds'+'to'='addsto'
'addsto' with letters rearranged gives 'AT ODDS'.
(Other definitions for at odds that I've seen before include "Conflicting (with)" , "In opposition or disagreement" , "Opposed, in conflict with" , "At variance (with)" , "Quarrelling" .)