Villa endured a turbulent ride last term, conceding 69 top-flight goals and keeping just five clean sheets leading to the club's worst defensive record of the Premier League era.
Clark was joined by 22-year-old Nathan Baker at the heart of Villa's penetrable defence last season, but the 24-year-old insists they have developed from their earlier errors.
The homegrown duo, alongside captain Ron Vlaar, are much improved this season, culminating in four clean sheets in their opening 11 fixtures.
Clark, who helped thwart both Norwich and Hull City before Barker joined him to shut out West Ham and Cardiff, believes the friendly rivalry between the pair is spurring them on.
"When you get on you have to try to take your chance and I think both of us have done that this season," Clark told the Birmingham Mail. "We've both played well and both want to be involved and play.
"We are good mates and if one of us is playing the other one will fully back the other lad. I think that's the kind of belief we've got here at Villa.
"Whoever's not playing wants the 11 players out there to do well and I think that will take us far.
"All last season we were learning the whole time. It was a young squad last year, and each game we played in we were learning. But last season's gone now and we need to concentrate on this year.
"We've had a very tough start. Considering the top sides we've played against, we've managed to pick up quite a few points.
"Hopefully we can get some consistency going, keep the belief and confidence that's there and we'll have a good season. It's always nice as a defender to keep clean sheets."
Fellow centre-back Jores Okore has been ruled out for the season with a cruciate ligament injury but Clark believes the solidarity brought by veteran duo Brad Guzan and Vlaar is also aiding his learning.
"It's not nice to see any of the lads get injured," Clark added.
"All our thoughts are with Jores and hopefully he can come back fit and well as soon as possible, that's the main thing.
"Both Brad and Ron have been brilliant for us last season and this. To play alongside both of them is brilliant for me.
"They're both experienced players and I think they're both coming into their own really. I'll obviously keep learning more and more playing with those two."