Indifferent emergency appeal gains nought (2-2)
I believe the answer is:
so-so
'indifferent' is the definition.
(synonyms)
'emergency appeal gains nought' is the wordplay.
'emergency appeal' becomes 'sos' (I have seen 'urgent appeal' mean 'sos' so perhaps 'appeal' could also mean 'sos'. I am not sure about the 'emergency' bit.).
'gains' means one lot of letters go next to another.
'nought' becomes 'o'.
'sos'+'o'='SO-SO'
Can you help me to learn more?
(Other definitions for so-so that I've seen before include "Nothing to write home about" , "Barely passable" , "'Passable, middling (2-2)'" , "Fair to middling" , "just about adequate" .)