But it sounds like all! (4)
I believe the answer is:
some
'but' is the definition.
Both the answer and definition are adverbs. Perhaps they are linked in a way I don't understand?
'it sounds like all' is the wordplay.
'it sounds like' shows a homophone (sound like).
'all' becomes 'sum' (I've seen this before).
'sum' sounds like 'SOME'.
Can you help me to learn more?
(Other definitions for some that I've seen before include "certain" , "Hard work" , "Undefined number" , "Part" , "An unspecified quantity, not all" .)