According to Daily Mail, Clarke started gambling online and even impersonated Gordon's son Andrew to have $7 million transferred into one of his private accounts.
The court heard how Clarke would regularly place bets of up to $1.5 million on a sporting match and would bet on several matches a day in an attempt to "double" his money and pay back what he stole.
"In the last few days of his offending he was betting an average of over $3 million per day on football games around the world," Judge Williams said.
"For example, he bet $1.2 million on two American football games, $1 million on a New Zealand provincial rugby game, and $1.5 million on a rugby league match between Sydney Roosters and North Queensland Cowboys."
Clarke was fired when the allegations were first made. He was sentenced to a three-year non-parole period, with a maximum sentence of six years' imprisonment.