A pre-race incident looked as if it would cost trainer John O'Shea his first stakes win for Sheikh Mohammed's Darley operation but Cameo stepped up to the plate to win the Scone Cup.

Just hours before Friday's race, Darley's other runner Wistful, the $4.80 favourite, was scratched after arriving at the track injured.

It was the third Scone Cup win in the past four years for Darley with Dysphonia successful in 2011 and Raspberries in 2012 when Peter Snowden was the head trainer.

O'Shea took over from Snowden earlier this month.

"She hit her head in the truck and opened it up," Darley general manager Henry Plumptre said of Wistful.

"Craig Suann, the Racing NSW vet, is here and he inspected her.

"We will rely on Craig's advice but I don't think we will stitch it."

Although Cameo originally went into the Cup as Darley's second stringer and was a $21 chance, Plumptre defended her recent record of finishing last or near last at her past four metropolitan runs.

"They were all on rain-affected tracks and from wide barriers and she does not like those conditions," he said.

"She is a good mare on good going and with a good draw, and she had both today.

"That was a gem of a ride from Sam (Clipperton)."

Plumptre said Cameo and Wistful would both go to Brisbane to run in the Lord Mayor's Cup.

"Wistful will race on but Cameo will be going to stud," Plumptre said.

"It is frustrating when a horse suffers an injury like Wistful.

"These races are picked out months before and Peter did a wonderful job building them up and giving them the foundation they needed."

Champion Sydney apprentice Clipperton jumped Cameo on terms with the rest of the field from her inside barrier and settled her in sixth place on the rails.

He started to edge forward coming to the turn, went around the early leader Collar in the straight then held on to win by a length from the Peter Moody-trained Full Of Spirit.

It was Clipperton's first stakes win for the stable.

"I have ridden a handful of winners for Darley but this is my first black type race for them," Clipperton said.

Clipperton's victory was later tempered somewhat in the stewards' room when he was suspended for a week for causing interference in an earlier race and also fined $200 for flourishing his whip on the line in the Cup.

Clipperton starts his suspension on Sunday, May 25 and can resume riding the following Sunday.