Playing on their new 4G pitch, which was officially opened beforehand by Ireland head coach Joe Schmidt and IRFU president Martin O’Sullivan, Clontarf scored the game’s only try in the first half through strong-running centre Matt D’Arcy.
D’Arcy spotted a gap in midfield and finished off in clinical fashion, with Rob Keogh converting and kicking three penalties. Galwegians out-half Aidan Moynihan also landed three place-kicks, while winger Alan McMahon went close to squeezing over for a try in the corner.
Talented scrum-half Neil Cronin tallied up 18 points, including a try, as Garryowen overcame hosts Old Belvedere 28-13 at Anglesea Road. Nearby at Belfield, Barry Daly waltzed over for two tries as UCD enjoyed an eye-catching 39-10 triumph over defending champions Lansdowne.
The title holders suffered their third defeat in four league outings and were comprehensively outplayed by Noel McNamara’s students, who are now up to second in the table. They had braces from back-three stars Daly and Tom Fletcher, and a try apiece from Conall Doherty and Jamie Glynn.
Young winger Jake Swaine touched down twice as Terenure College dominated the final quarter to take a three-try 30-6 verdict over struggling Ballynahinch at Ballymacarn Park.
In Division 1B, Munster flyer Stephen Fitzgerald bagged a brace of tries as Shannon emerged as 32-10 bonus point winners over Belfast Harlequins at Deramore Park.
Dublin University chalked up their fifth success in-a-row when hammering Dolphin 44-3 at Musgrave Park.
Centre Seb Fromm scored either side of half-time, making it three tries in two games for the German Sevens international.
Old Wesley put an end to their two-match losing streak by winning a tightly-contested south Dublin derby 36-22 at Donnybrook.
Winger Barry McLaughlin’s clinching try took his already impressive league tally to 103 points after seven rounds.
Ireland Sevens starlet Terry Kennedy’s late try earned a 27-24 bonus point success for Division 1B leaders St Mary’s College as they battled past a durable UL Bohemians team at Annacotty.
Meanwhile, Matthew Rea crossed the line for the second week running as second-placed Ballymena got back to winning ways by edging out Buccaneers 15-14 under the Dubarry Park floodlights.