Sacked in the wake of England's 5-0 whitewash in Australia in 2013/14, 34-year-old Pietersen may be set for an unlikely recall if he racks up the runs for Surrey in English county cricket.
He scored 170 on his return for the side on Sunday, albeit in a non-first class match against Oxford MCCU.
“I do think he could be at the Ashes,” Clarke told reporters in Melbourne on Friday after announcing a two-year deal to play Twenty20 cricket in Australia's domestic 'Big Bash' competition.
“His form, he's showed that, he's certainly scoring enough runs.
“He's made it very clear he wants to play and now it will come down to the England selectors.”
England's selectors have repeatedly dismissed the idea of Pietersen ever re-joining the team, but the South Africa-born right-hander told the BBC he had been offered a “lifeline”.
Pietersen has been described as a divisive figure in the dressing room and trashed a number of his former team mates in his autobiography last year, but would be hard to overlook for the Ashes in July and August if he piles up the runs for Surrey.
He had a modest series by his lofty standards in the last Ashes but still managed to top England's runs list.
He sealed England's memorable 2005 Ashes win with a glittering 158 at the Oval on the final day of the series and also belted 227 in the Adelaide test during his team's 3-1 win away to Australia in 2010/11.
Clarke, who retired from one-day cricket after Australia's fifth World Cup triumph last month, will have first-hand experience of the dressing room vibe with Pietersen as the batsman's captain at T20 side Melbourne Stars.
Pietersen proved a smash hit in his first tournament with the Stars, clubbing 293 runs at an average of 41.86.
“It's going to be nice to be on the same side,” Clarke said.
“To have that luxury as captain to have a player like that in your team is extremely exciting and I know he'll play a big part is us having success.
“At the moment, from the Australians' perspective, I'm happy if he's not playing (tests) because he's a wonderful player.” – Reuters
Original source: Clarke sees KP returning for Ashes