Australia, 71 for two at lunch after winning the toss, had a disastrous middle session, losing four wickets including two to Broad as the hosts went to tea on 153 for six.
Brad Haddin was on 24 and Mitchell Johnson was 12 at the break but the day so far belonged to Broad, who was vilified in the build-up for not walking during the recent Ashes Tests in England.
Broad also accounted for Shane Watson (22) just before lunch, and he then took the prized scalp of Australian skipper Clarke in the second over after the first break.
Clarke looked uncomfortable against a short-pitched delivery and popped a gentle catch to Ian Bell at short leg for one, in what was a quick and tame end for Australia's best batsman.
Opener David Warner had creamed Broad's first ball of the day for four but his determined innings ended with a whimper as he became the tall quick's fourth victim just short of his half-century.
