Chap cut up over celebrity singer (8)
I believe the answer is:
vocalist
'singer' is the definition.
(I know that singer can be written as vocalist)
'chap cut up over celebrity' is the wordplay.
'chap cut up' becomes 'voc' (I am not sure about this - if you are sure you should believe this answer much more).
'over' says to put letters next to each other (in a down clue, some letters go over others).
'celebrity' becomes 'a-list' (I've seen this before).
'voc'+'alist'='VOCALIST'
Can you help me to learn more?
(Another definition for vocalist that I've seen is " Singer with a pop group".)