Tottenham Hotspur could be set to miss out on a £10m transfer windfall with the sale of Dele Alli to Everton. It has been a difficult spell for the 27-year-old who has had to deal with some major off-field issues, as well as injury problems. The Toffees have not played the former England international this term and there are question marks over whether he’ll play at all before the summer. Everton have £10m Dele clause with TottenhamAccording to previous reports, Dele’s transfer to Goodison Park was largely incentivised by potential add-ons based on specific targets. However, the 27-year-old ha…