Hughes passed away after being struck on the head by a ball during a domestic cricket match last Tuesday, causing a catastrophic injury from which he never recovered, sending Australia and the world into mourning.
Clarke and the rest of the test squad gathered at Hughes' funeral at his home town of Macksville, 350 miles north of Sydney.
Clarke, who was also a pallbearer, spoke at the funeral and broke down a number of times as he said his last words to his late friend.
"Taken from the game, his family and loved ones at the age of just 25, he left a mark on our game that needs no embellishment. I don’t know about you, but I keep looking for him.
Clarke spoke of how Hughes' spirit brought many cricketers together and how it was still at work despite his death.
"His spirit has brought us closer together – something I know must be him at work because it is so consistent with how he played and lived. He always wanted to bring people together and he always wanted to celebrate his love for the game and its people.
"The bonds that lead to cricketers from around the world putting their bats out, that saw people who didn't even know Phillip lay flowers and that brought every cricketing nation on earth to make its own heartfelt tribute."
Clarke concluded: "Phillip's spirit, which is now part of our game forever, will act as a custodian of the sport we all love," he told mourners.
"We must listen to it. We must cherish it. We must learn from it. We must dig in and get through to tea. And we must play on."
The funeral was a national event - broadcast live on Australian television and on big screens across the country.
In pictures: Phillip Hughes funeral
Clarke has delivered a number of statements and speeches in the week since the death of Hughes.
He delivered a tribute to Hughes on behalf of players at the Sydney Cricket Ground at the weekend, stating: "We are going to miss that cheeky grin and that twinkle in his eye...The world lost one of its great blokes this week and we are all poorer for it.
"His legacy of trying to improve each and every day will drive us for the rest of our lives.
"Our dressing room will never be the same. We loved him and always will. Rest in peace bruzzy."
Clarke also delivered a statement from Hughes' family to the media last Thursday shortly after the cricketer's death was announced.
The funeral lasted 80 minutes, with Cricket Australia chief James Sutherland saying: "I imagine Phillip had already taken guard up there and is currently flaying his trademark cut shot behind point.
"Cricket's heart has been pierced with pain, but it will never stop beating."
Hughes, who had played for English counties Hampshire, Middlesex and Worcestershire, had been involved in 26 Tests for his country, having made his debut at the age of 20 against South Africa in 2009.Reuse content