Grip (or �bite�) is an expression used to describe a wine that has a noticeable tannin or acid component. In young wines this is sometimes an indication that the wine will age well, with the tannins softening with maturity.
As with all wine, however, it�s a matter of balance. Too much tannin in a red wine or too much acidity in a white wine can result in a harshly unpleasant drink. A good wine should taste good from the beginning of its life, merely changing and accumulating charm as it ages. Don�t expect a nasty, rough young wine to develop into something grand.