Unpleasant chart topper going on a bit (7)
I believe the answer is:
noisome
'unpleasant' is the definition.
(I've seen this before)
'topper going on a bit' is the wordplay.
'topper going' becomes 'noi' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' says to put letters next to each other.
'a bit' becomes 'some' (I've seen this in other clues).
'noi'+'some'='NOISOME'
'chart' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for noisome that I've seen before include "Odious" , "Nauseating" , "Smelling bad" , "Unpleasantly smelling" , "unhealthy" .)