How to draw subsection of text using .net graphics

//get the actual bounds of this  entire item spanning across multiple cells
RectangleF sRectF = GetItemRectF(startX + leftMargin + 2, widthForItem, cellBounds, calItem);

//we clear it out first, otherwise the text looks bolded if we keep drawing a black string over and over
//todo should figure out how to only draw this cells section? cellBounds subsection of sRectF somehow
graphics.DrawString(calItem.Description, new Font("Tahoma", 8), new SolidBrush(itemBackColor), sRectf);
graphics.DrawString(calItem.Description, new Font("Tahoma", 8), new SolidBrush(Color.Black), sRectF);

Region tempRegion = graphics.Clip;
graphics.Clip = new Region(cellBounds);
graphics.DrawString(calItem.Description, new Font("Tahoma", 8), new SolidBrush(Color.Black), sRectF);
graphics.Clip = tempRegion;