try bleeding the clutch, but if you have a whole lot of city miles on it, or just got the car used and dont know its history, chances are you need to just replace the clutch. The pressure plate springs are possibly worn out and/or the disk is worn, if youve felt slipping and the engine roars when you give it the gas (jumps past normal rpm) then you need a clutch. You might want to take it to a shop that offers (preferably free) diagnosis first.
adjusting the clutch might or might not work and at best, is only a temporary fix. If adjusting works it will sometimes buy enough driving time for you to round up the parts or get it to the shop without needing a tow.
The way to test your clutch is a little bit tough on the drive train so i wouldn't do it more than once...(in fact if i felt it slipping i'd just change the clutch instead of testing it like this). you drive the car to a street or lot with nothing to hit for a long ways in front. Set the parking brake good and tight, rev the engine about 2,000 rpm, put the trans in second. pop the clutch and let off the gas at the same time. The engine should quickly stall. If it doesnt, you probably need a new clutch.