partisan - Dictionary definition and meaning for word partisan
parti(think of a political party)+san(son)...so a father who is favouring his son's political party, instead of a good party.
just d way civism is being a good citizen, partism (reminds of partisan) is being a good(ardent) supporter of a party/group/person/activity
PARTison -> taking a PART or side
Partisan almost sounds like "party-fan".. Someone who strongly supports partying it up :)