Help! Nothing is tolerable! (2-2)
I believe the answer is:
so-so
'tolerable' is the definition.
(thesaurus)
'help nothing' is the wordplay.
'help' becomes 'SOS' (emergency abbreviation SOS).
'nothing' becomes 'O' (looks like zero - 0).
'sos'+'o'='SO-SO'
'is' is the link.
(Other definitions for so-so that I've seen before include "'Passable, middling (2-2)'" , "Barely passable" , "just about adequate" , "Informally, only moderately good or well" , "Tolerable, indifferent" .)