Brett Butler has been plying her trade as a stand-up in honky tonks and comedy clubs for a dozen years in relative obscurity. In a few weeks, she’s likely to lose her anonymity.For as the star of the new ABC sitcom “Grace Under Fire,” programming analysts are overwhelmingly pointing to the Georgia-bred Butler as the most-likely-to-succeed new talent in the fall TV season. It’s amazing, considering Butler has no previous acting experience. Carsey-Werner Co. VP David Tochterman was scouting talent on ABC’s request to develop a sitcom about a single mother when he discovered Butler a few months ago. Butler realizes she’s lucky, but she’s also confident she has the right stuff. “I know there was a certain amount of providence involved that Carsey-Werner saw me at all,” said Butler. “But, I can do this. I can act.” Butler thinks her stage experience has a lot to do with it. She has a knack for mimicking accents and had been considering trying acting for some time. “I was thinking, hell fire, I should be in a play,” said Butler, in her slightly Southern-twanged speech. Actor friends had been encouraging her too. So far, Butler hasn’t needed much coaching. “They (the producers) just tell me to ‘keep doing what you’re doing. Be who you are,’ ” she said. Butler isn’t playing herself in “Grace Under Fire.” In real life, Butler is happily married and has no children. But she and Grace Kelly (yes, that’s the character’s name) share a similar down-to-earth, outspoken quality. She believes Carsey-Werner chose her for the part because of it. “They liked the mouth on me, ” said Butler.