Bad side dominated by Millwall initially (6)
I believe the answer is:
malign
'bad' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for malign that I've seen before include "Speak ill of; evil" , "Defame, vilify" , "Wicked, evil" , "Bad-mouth" , "Evil, baleful" .)