Go back again with a terrible fellow (4)
I believe the answer is:
'a terrible fellow' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'go back again' is the wordplay.
'back' shows that the letters should be reversed in order.
'again' becomes 're' (prefix meaning 'again').
'go' back-to-front is 'og'.
'with' is the link.
Can you help me to learn more?
(Other definitions for ogre that I've seen before include "Monster, troll" , "'Demon, fiend (4)'" , "ugly one" , "Grim(m) beast?" , "Cruel fairytale giant" .)