Dull sound of one day following another (4)
I believe the answer is:
thud
'dull sound' is the definition.
(I've seen this in another clue)
'one day following another' is the wordplay.
'one day' becomes 'thu' (abbreviation for Thursday).
'following' is a charade indicator (letters next to each other).
'another' becomes 'd' (I can't explain this - if you can you should give a lot more credence to this answer).
'thu'+'d'='THUD'
'of' is the link.
Can you help me to learn more?
(Other definitions for thud that I've seen before include "Dull sound of impact" , "Sound of heavy blow" , "Clunk" , "Clonk" , "Dull bang" .)