Key to do more about apathy (7)
I believe the answer is:
boredom
'apathy' is the definition.
(thesaurus)
'key to do more about' is the wordplay.
'key' becomes 'b' (eg B major, musical key).
'to' means one lot of letters go next to another.
'about' indicates anagramming the letters.
'do'+'more'='domore'
'domore' is an anagram of 'oredom'.
'b'+'oredom'='BOREDOM'
(Other definitions for boredom that I've seen before include "no interest" , "Overseers" , "weary idleness" , "Mental state" , "Ennui in bedroom" .)