Useless expenditure in central region, by the sound of it (5)
I believe the answer is:
waste
'useless' is the definition.
(similar in meaning)
'by the sound of it' is the wordplay.
'by' means one lot of letters go next to another.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'sound of' becomes 'was' (I can't explain this - if you can you should believe this answer much more).
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
't' after 'was' is 'wast'.
'wast'+'e'='WASTE'
'expenditure in central region' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for waste that I've seen before include "Barren area; rubbish" , "Unwanted material" , "Rubbish, barren land" , "Become gradually weaker" , "Blue" .)