The teenager’s previous best bowling figures were 5-31 for Hambledon 2nds against Bedhampton 2nds in the Hampshire League in 2019.
But the left-arm seamer bettered that with a 5-14 burst for the 1st XI as Purbrook were dismissed for 109 to lose by 54 runs at The Ridge.
James Restell dismissed Purbrook openers Clark Harding (3) and Sean Figgins (17) before Khan, introduced as first change, took centre stage.
He started by having captain Josh McCoy (19) caught behind by Mark Butcher before dismissing Hayden Sole (1) and Richard Nichol (18).
Purbrook, who had been 48-2, lurched to 63-6 when Brad Mengham (0) was caught by Henry Glanfield to give Khan his fourth wicket.
Khan later wrapped up the innings when he clean bowled No 10 Aaron Dean, his side’s top scorer with 21.
Earlier, George Marshall (56 not out) had top scored as Hambledon, inserted after losing the toss, posted 167-6 in a game reduced to 32 overs a side.
Opener Daniel McGovern scored 37 on his Hambledon league debut and Chris Pratt (27) helped Marshall add 65 for the fourth wicket.