Arif, making his first-class debut, upstaged England's 2005 Ashes-winning seamer Simon Jones but it was Jones, playing against his former county, who broke Glamorgan's opening stand of 42 by dismissing Richard Grant.
The spotlight then turned to Kashmir-born Arif when he revealed genuine pace in a spell of 3-22 in six overs.
Although he has a British wife and a UK work permit, he has a Pakistan passport and came into the Worcestershire team on an overseas registration.
Taking a wicket with his 13th delivery - David Hemp flashing a catch to wicketkeeper Steve Davies - he then stuck twice in his fourth over.
Davies held a chance from Michael Powell at the second attempt and Jamie Dalrymple was lbw to the second ball he faced.
Opener Gareth Rees survived the crisis to reach an unbeaten 59 and Mark Wallace (37no) played positively in their unbroken stand of 80.
The day had started with Worcestershire piling up the runs as Davies and Smith compiled Worcestershire's biggest Championship partnership of the summer.
The fifth-wicket pair put on 143 in building up to the declaration.
Some of Smith's driving past extra cover was top class and Davies pursued his strengths outside the off stump in his finest innings of the season.
David Harrison and Jason Gillespie bowled economically but without much luck, and it was teenager Harris who removed both batsmen in successive overs from the New Road end.
Smith was only one short of his first hundred in two years when he looped a lifter to first slip and Rees held a stunning catch at point to remove Davies for 83.
Worcestershire's lower order scored briskly to embellish their total.