The son of Dalakhani completed a hat-trick with his first victory outside of handicap company in the Listed Glasgow Stakes at Hamilton last Friday.
"I'm not quite sure where Defoe's next run will be, but I would very much like to get him to the St Leger in peak condition," said Varian.
"He shapes like he is an improving horse and he shapes like he will stay further, and that he will possibly get better over further.
"It was good that he won at Hamilton as that had been the plan for a few weeks.
"He's come out of that race well."
Stablemate Madeline is set to run in the Group Two Lowther Stakes at York next month.
The daughter of Kodiac finished fifth in the Albany at Royal Ascot and followed up with victory in a Listed event at Newbury last Friday.
The Newmarket handler said: "Madeline put in a good performance at Newbury and she is improving.
"I think she deserves a crack at the Lowther and that is likely to be her next start.
"She is a real two-year-old type. We will not worry about next year yet, as there are plenty of races still to go for this year and hopefully add to her CV."
The Newmarket handler intends to step Morando up in class ahead of a potential outing in the Queen Elizabeth II Stakes at Ascot on Qipco Champions Day in October.
Having missed the early part of the season, the lightly-raced four-year-old made it four wins from six starts in a Listed contest at Windsor on his return on July 1.
Varian said: "He is a very progressive horse and should have a good back-end to the season.
"There was no major reason he was out. Obviously he was winter favourite for the Lincoln and he was not quite ready.
"He took a while to come to himself. He goes better with juice in the ground, so that is why we didn't turn up for the Royal Hunt Cup.
"We'll step him up now and look for a Group Three for him.
"He will get an entry in the Queen Elizabeth II Stakes, but we have got an awful long way to go to talk about him being a Group One horse.
"He is lightly raced, though, and his best days are still ahead of him."