BUZZ-Debenhams: weak margin guidance
** Department stores chain Debenhams (Other OTC: DBHSF - news) slides 7.8 pct, poised for biggest one-day pct drop in a yr as its margins come under pressure
** Warns weaker clothing demand & higher sales of low-margin categories mean FY rise in gross margin would be at the lower end of guidance
** One bright spot was strong improvement in Christmas trading; had dire Christmas in 2013 when it was forced to warn on profits
** Busy day for UK retailers: robust Xmas performances lift baker Greggs (LSE: GRG.L - news) to all-time high & boost shares in Wm Morrison & online fashion retailer ASOS (RM (LSE: RM.L - news) : tricia.wright1.thomsonreuters.com@reuters.net)