The Czech striker has scored four goals in 14 Premier League appearances for Paul Lambert's men since signing from Lazio in September, but is set to miss the rest of the season after sustaining the injury in training last Thursday.
His absence is as a blow for a Villa side that have only registered 19 goals in the top flight this season.
But Clark believes the Czech Republic international will bounce back from his major setback.
"He's had his treatment and hopefully he'll come back stronger," he told the club's official website. "All the lads are thinking of him. Hopefully he'll make a full recovery.
"We were playing a possession game and it was a clash of legs. No-one expected it and we thought he was going to get back up. The physio came on and knew it was a bad injury.
"I didn't sense anything was wrong and I don't think anyone did. At the time people thought it was a normal challenge.
"I don't know if it was the impact of the way his leg went but it was innocuous and no-one expected it to be as bad."
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