Mathieu van der Poel (Corendon-Circus) tightened his grip on the overall lead in the Tour of Britain, following a dominant win in Stage 7 at Burton Dassett Country Park in Warwickshire.The Dutchman went head-to-head with closest rival Matteo Trentin (Mitchelton-Scott) of Italy on an uphill sprint to the finish and proved the stronger of the pair after putting in a final kick over the last 150 metres.Australia's Simon Clarke (EF Education First) crossed the line at the head of the peloton three seconds down on the stage winner. Van der Poel now holds a 12 second lead over Trentin in the General Classification, with only the eighth and final stage in Manchester to come.