Not many, but it sounds more than is needed (3)
I believe the answer is:
two
'not many' is the definition.
(I've seen this in another clue)
'it sounds more than is needed' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
The remaining letters 'wo' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'but' is the link.
Can you help me to learn more?
(Other definitions for two that I've seen before include "eg Twins" , "Minimal number of partners" , "Figure" , "Number in pair" , "''... turtle doves''" .)