A nymph from the underworld avoiding a goddess (5)
I believe the answer is:
diana
'a goddess' is the definition.
(Roman goddess)
'a nymph from the underworld avoiding' is the wordplay.
I cannot really see how this works, but
'a' could be 'an' and 'an' is found in the answer.
The remaining letters 'dia' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for diana that I've seen before include "Dame - Rigg, actress" , "British princess" , "female" , "Roman huntress goddess" , "Roman goddess equating to Artemis" .)