Tinshu landed her fourth course-and-distance success when repeating last year's victory in the Dormansland Handicap at Lingfield.
It was a timely triumph for the six-year-old mare as she is going to the Tattersalls December Sale next week.
Jockey William Carson was never too far off the pace set by Spifer and got a dream run on the rails.
Tinshu (5-1) quickened nicely and held the late thrust of Robin Hoods Bay by a neck, with the fast-finishing Emerald Wilderness third.
"She's for sale on Monday at the December Sales, but she won't be going for nothing," said trainer Derek Haydn Jones.
"With the form she's in now, the plan is if she doesan't sell she'll come back for the Listed race she won here last year."
Carson said: "Last time here the race didn't go plan. I had instructions to stay closer to the pace and she's pulled out all the stops."
The rider was completing a 29-1 double after earlier steering home the Stuart Williams-trained The Strig (4-1 co-favourite) in the Betfred Mobile Sports Handicap.