Clarke made a surprise reappearance at the crease on Wednesday morning having retired hurt shortly before tea on day one after twisting away from an Ishant Sharma bouncer.
The 33-year-old went on to notch his fourth consecutive Test hundred at the Adelaide Oval, taking his average at the stadium to a staggering 100.50, as Australia closed on 517-7.
Smith was full of praise for Clarke???s batting but also saluted his captain???s ???unbelievable??? bravery in the wake of the tragic death of batsman Phillip Hughes.
???He just came out and played beautifully,” Smith, who remains 162 not out overnight, said of Clarke.
“I think a few shots hurt him but he got himself into as many good positions as he could and he manipulated the field a little bit as well.
???He has done amazingly over the last couple of weeks, spending the whole time by Hughesy’s family’s side. Just the strength and courage he has shown through those times was unbelievable.
“He must be mentally drained coming into this game but the way he played speaks the world of that guy. He came out here and tried to do something for Hughesy and he certainly did that.”
Clarke and Smith???s centuries, which were secured during a seventh-wicket stand of 163, followed on from the ton posted by New South Wales team-mate David Warner (145) on day one.
Smith says the hundreds were poignant, with Hughes playing against New South Wales, for South Australia, when he was struck by that fateful bouncer in a Sheffield Shield match in late November
“The last couple of weeks have been very tough for every one of us,” added Smith, who now has five Test hundreds to his name.
???We’re all good mates with Hughesy, us three (Clarke and Warner), so I was sort of hoping all three of us would get runs and it worked out well for us in the end.
“I know that’s what Hughesy would have wanted ??? all of us to be out here doing the job ??? and he was with me, Pup (Clarke) and Warner all the way this innings.
???I think my hundred at Centurion against South Africa (in February) would probably be my best one so far in my book, but every hundred’s nice and hopefully I’ve got a few more this summer.???