Dull sound when round gong that's fingered (7)
I believe the answer is:
thumbed
'fingered' is the definition.
('thumb' can be a synonym of 'finger')
'dull sound when round gong' is the wordplay.
'dull sound when' becomes 'thud' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'round' means one lot of letters goes inside another.
'gong' becomes 'MBE' (Member of the Order of the British Empire award).
'thud' enclosing 'mbe' is 'THUMBED'.
'that's' is the link.
Can you help me to learn more?
(Another definition for thumbed that I've seen is " Cursorily leafed through".)