Mark, journalist, has 60s singer round (7)
I believe the answer is:
cedilla
'mark' is the definition.
(I know that cedilla is a type of diacritic)
'journalist has 60s singer round' is the wordplay.
I cannot quite see how this works, but
'journalist' could be 'ed' (short for editor) and 'ed' is found in the answer.
The remaining letters 'cilla' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cedilla that I've seen before include "Small mark placed below C in Portuguese and Catalan, for example" , "Mark under the letter C in French" , "I called (anag.)" , "Mark indicating a softened consonant" , "Mark, in foreign language" .)