City boss Yves discharged diary keeper (5)
I believe the answer is:
pepys
'diary keeper' is the definition.
(I know that Pepys is a diary keeper)
'city boss yves discharged' is the wordplay.
'city boss' becomes 'pep' (I can't explain this - if you can you should give a lot more credence to this answer).
'discharged' says to hollow out the word (remove centre letters) (the letters inside the word released or discharged).
'yves' with its centre removed is 'ys'.
'pep'+'ys'='PEPYS'
Can you help me to learn more?
(Other definitions for pepys that I've seen before include "Journalist" , "London diarist" , "English civil servant and diarist, d. 1703" , "Samuel, diarist, d. 1703" , "Samuel -, noted diarist" .)