Being at variance adds to problems (2,4)
I believe the answer is:
at odds
'being at variance' is the definition.
(thesaurus)
'adds to problems' is the wordplay.
'problems' indicates anagramming the letters (I've seen 'problem' mean this).
'adds'+'to'='addsto'
'addsto' anagrammed gives 'AT ODDS'.
(Other definitions for at odds that I've seen before include "Quarrelling" , "At variance (with)" , "Conflicting (with)" , "In disagreement or conflict - like bookies?" , "Opposed, in conflict with" .)