Littler was booed by sections of the M&S Bank Arena crowd throughout Night 12, but responded in emphatic fashion, beating Luke Humphries, Michael van Gerwen and Clayton to close the gap at the top of the table.
The world No. 1 saved his best performance for the final, overpowering Clayton in a high-quality contest that featured 11 maximums in just seven legs.
Clayton, who had won the previous two nights in Rotterdam and Manchester, landed five 180s of his own, but Littler produced six and punished his opponent's missed chances to seal a convincing win.
The teenager opened with an immediate break of throw and quickly moved 5-0 ahead, before Clayton avoided the whitewash. Littler then returned to close out victory on tops and continue his pursuit of the league leader.
Earlier in the night, Littler defeated Humphries 6-2 in a result that leaves the reigning Premier League champion in a precarious position in the race for Finals Night.
Humphries averaged slightly higher than Littler, but his doubling proved costly as he missed a string of chances in the early legs and fell 4-0 behind. Littler eventually completed the win on double 4, offering little celebration after a business-like performance.
Littler then edged Van Gerwen 6-5 in a thrilling semi-final, despite the Dutchman averaging 107 and hitting nine maximums. Van Gerwen led 3-1 and 5-4, but Littler fought back, taking out 90 on double 15 before holding throw in the decider with a clinical 46 checkout.
Clayton reached the final after two last-leg victories, first beating Stephen Bunting 6-5 before edging Gian van Veen by the same scoreline.
Bunting, backed heavily by his home Liverpool crowd, missed a match dart at D18 before Clayton returned to finish double 8. Van Veen then pushed Clayton all the way in the semi-final, but the Welshman survived after the Dutchman missed the bull for a 167 finish in the deciding leg.
Van Veen had earlier produced one of the results of the night by beating Gerwyn Price 6-4 in the opening quarter-final, while Van Gerwen defeated Josh Rock 6-3 to boost his own play-off hopes.
Night 12 results
Quarter-finals
Gian van Veen 6-4 Gerwyn Price
Jonny Clayton 6-5 Stephen Bunting
Michael van Gerwen 6-3 Josh Rock
Luke Littler 6-2 Luke Humphries
Semi-finals
Jonny Clayton 6-5 Gian van Veen
Luke Littler 6-5 Michael van Gerwen
Final
Luke Littler 6-1 Jonny Clayton