Poor Democrat is with Scomo's predecessor (6)
I believe the answer is:
dismal
'poor' is the definition.
(dismal can mean poor or bad-quality)
'democrat is with scomo's predecessor' is the wordplay.
'democrat' becomes 'd'.
'with' is a charade indicator (letters next to each other).
'scomo's predecessor' becomes 'mal' (I can't justify this - if you can you should give a lot more credence to this answer).
'd'+'is'+'mal'='DISMAL'
Can you help me to learn more?
(Other definitions for dismal that I've seen before include "Gloomy and cheerless" , "'Depressing, grim (6)'" , "Sad and dreary" , "Gloomy, dreary" , "Very disappointing" .)