As the lead singer of Trick Pony, Heidi Newfield established herself on country radio in the ‘90s with frothy fare like “Pour Me” and “On a Mission,” but her solo debut album What Am I Waiting For has a more substantial feel. Produced by veteran hit-maker Tony Brown, these tracks are in a classic country mode, boasting above-average songwriting and well-tailored arrangements. Newfield’s vocals — tempering a rough edge with a honey-smooth delivery — recall those of such sultry chanteuses as Bobbie Gentry and Sammi Smith. Those looking for sassy Trick Pony-like exercises will be pleased by “Nothin’ Burns Like a Memory” and especially “Knocked Up.” But tormented ballads like “Love Her and Lose Me” (a plainspoken confession worthy of Tammy Wynette) and “Wreck You” (an unsparing portrait of a crumbling marriage) are the real showpieces here. Not all is sorrow though; “Johnny and June” celebrates Mr. and Mrs. Cash, while the title number tingles with dawning optimism. Stretching out a little, Newfield does a credible job with “Can’t Let Go,” a song previously cut by Lucinda Williams. What Am I Waiting For is an impressive, often revelatory album by an artist who’s left the trickery behind.