Treviso did mount an impressive fightback, only for the boot of Steve Shingler to seal a 22-20 triumph - an eighth win in nine league games this season for Wayne Pivac's side.
And Barclay was relieved to have denied the Italian hosts their first GUINNESS PRO12 win of the season.
"We've always come away to the Italian teams and struggled a little bit," he said. "We started well today; to be fair we didn't expect them to play with so much width.
"We felt we let them back in the game a little bit with some ill discipline. They were pretty accurate and they came back into it. We felt if we got back down there we could score because of the way we were playing when we had the ball.
"At the end of the day we've come away with another win so we're happy.
"It's nice but you don't get anything for being top of the table at this stage in the season. It's a long season and we've only played nine league games.
"It's nice now with two European games to sit there and look at it and think we've worked pretty damn hard to get there and we've played some scrappy games. I don't think we've played our best rugby but we're grinding out good wins. It's pleasing but it's still early days.
"There's also not a great deal separating one to four, you get very little at the end of the season for saying we were top after nine games, we'll keep our heads down. Teams will still expect to be able to beat us because we haven't been top four for a couple of years.
"It's up to us to keep plugging away and show them that it's not just a fluke at the start of the season."
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