The Romans imagined him having a bit of bad luck in a van (6)
I believe the answer is:
vulcan
'the romans imagined him having a bit' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'bad luck in a van' is the wordplay.
'bad luck' becomes 'ulc' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'ulc' placed into 'van' is 'VULCAN'.
'of' is the link.
Can you help me to learn more?
(Other definitions for vulcan that I've seen before include "Roman god of fire and metalworking" , "Bomber" , "Greek god of fire" , "V-bomber; god" , "Roman smithing god" .)