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COLLINGWOOD coach Nathan Buckley says Irishman Marty Clarke has returned to the Magpies determined to taste success after walking out two years ago and missing their back-to-back Grand Final appearances.

Clarke, 24, returned from Ireland last month after he quit the club at the end of 2009 to go home and play Gaelic football for County Down, and study teaching. 

"He's been excellent. He really applied himself in his time off," Buckley said on Monday.

"It's interesting, when you talk about hunger. Marty's got a bit to prove.

"He hasn't been a part of the last couple of years. He obviously wasn't a part of the premiership season so he's come in with a fair bit to prove and he feels indebted to the faith that's been shown.

"His training has been excellent, his intensity's great and he's really driving the young fellas in particular."

Clarke was pre-listed by Greater Western Sydney and then traded to the Magpies in the October trade period after deciding earlier in the year he wanted a second chance.

Buckley said Clarke was the "obvious" choice to replace retired Pie Leon Davis in the role of a half back in 2012 but there were other candidates available.

"His fitness is right up. There's no reason why he can't go through the midfield or even play forward," he said.

"Leon is a big loss for us as far as that run and carry off half back goes but Ben Johnson probably played more midfield last year than previously and he can go through the half back, and Luke Rounds and Ben Sinclair have played time there in 2011 so there's no reason why they can't stand up there and assume the role."

Unlucky defender Nathan Brown participated in Monday's session at Gosch's Paddock but won't travel to Arizona with the squad on Tuesday when it heads off on its yearly altitude training camp.

A slimmed-down Brown looked fit and moved smoothly during the hit-out, but will stay in Australia to work on his rehabilitation from the two knee injuries - a reconstruction on his right leg in February and surgery to repair a split kneecap on his left in June.

"He loves work, he spends a lot of time down at the club even in his off season and he's had a wretched run in the last 12 of months," Buckley said.

"We're encouraged by the fact he's up and about, he's enjoying being out and doing ball work with the boys and he's probably trimmed a couple of kilos down.

"It's probably part of the program to make sure he gets back in good nick."

Captain Nick Maxwell missed Monday's session but will go to Arizona while Buckley said Andrew Krakouer would not, owing to the same US visa issues related to his criminal conviction and time served in prison that blocked his travel 12 months ago.

Buckley also said he believed Alan Didak "still had the attributes to be a good player for us" after a frustrating 2011. Buckley said the focus over summer with the premiership forward would be to rebuild his fitness so he could return to his best in 2012.