The 18-year-old had never played football beyond kick-to-kick with friends before to joining the Oakleigh Chargers TAC Cup team in 2008.
The immediate success he had in being picked for Vic Metro at the NAB AFL Under-18 championships led to him recasting his goal of playing US college basketball.
Fremantle duly selected him with pick No.37 at Saturday's NAB AFL Draft and now he is living with, and learning from, All-Australian ruckman Aaron Sandilands.
Coach Mark Harvey knows taking a player with so much development ahead of him might be a risk, but he's confident the 204cm Clarke will become an AFL ruckman.
"Zac's had a limited time playing football and he's evolving. When the guys all got here, we had a barbecue and Zac and Aaron both filled up on food. Aaron thought that was the end of it, but when he got home Zac was raiding his pantry looking for more food," Harvey said.
"He has only played for 12 months and that's the intriguing part, to see how we can develop him over the next couple of years. Naturally on the back of us needing some back up for Aaron he was a guy we targeted and are really happy to get."
Clarke never thought of being an AFL footballer until representing Vic Metro and despite only having played competitively for one season, he has now forgotten his basketball ambitions to focus on the oval ball.
"I remember 12 months ago when I got invited down to Oakleigh I wasn’t sure about going and when I did my aim was to just play a couple of games. To be here now is just amazing. Midway through the year it was really tough to make a choice, but I made the Vic Metro squad and that pushed me towards football," Clarke said.
"I was starting to look towards colleges in America, but that has stopped now. I'm 100 per cent committed to football. I've dropped basketball after having a future there and have decided to pursue footy and I will give it my all."
In his early days in Perth, Clarke already is making an impact, especially when he and Sandilands go together to the shopping centre.
"We do get a few looks when we go shopping. I just kind of smile and keep walking."
And Clarke has told the coach that he will push Sandilands out of the No. 1 ruck spot after just one year.
"I said one year, but I apologised to him last night," he said.
