HERBLOCK has struck again. In his 10th book, Herblock at Large (Pantheon. 224 pp. $16.95), the dean of American political cartoonists once again clobbers the incumbents. Not for him the rapier, the subtle thrust; his preference is for the direct approach -- the crowbar, the mallet, the battle-ax right on the noggin. How unpleasant to be his target! Surely even the secretary of defense must cringe at being framed in a $640 toilet seat, and President Reagan -- by all accounts a man who enjoys a joke -- cannot relish very much his depiction as an absent-minded bumbler. Clearly, however, a political cartoon pierces to the heart of an issue the way no prosy editorial can.

This new Herblock volume follows the fortunes of the Reagan administration from the morning after its 1984 election victory to the aftermath of the Iran-contra affair, a collapse of political fortune not exactly unapplauded by Herblock. An acerbic text ("Never before has there been so . . . much raising of flags while lowering of standards") accompanies and interprets the several score drawings, many of which will no doubt end up in history books a century hence.

Some of the caricatures are undoubted masterpieces, like the one of Kurt Waldheim being shadowed by his younger self in Wehrmacht uniform -- the caption reads "Marathon Man." Herblock's partisan spirit is well-known, but perhaps even his opponents might concede that at all times he is for candor, for human liberty, for the have-nots against the haves. It seems hard to believe, but he has been drawing for The Washington Post since 1946, in that time winning three Pulitzer Prizes and sharing a fourth.