Future electric power systems will face new operational challenges due to the high penetration of distributed energy resources (DERs). In Denmark, distribution system operator (DSO) expects a significant congestion increased in distribution grids. In order to manage these congestions and mobilize the DERs as economically efficient as possible in the future distribution grid, the brand newnotion of flexibility clearing house (FLECH) is proposed inthis paper. With the aggregator-based offers, the proposed FLECH market has the ability to promote small scale DERs(upto 5 MW) for actively participating in trading flexibilityservices, which are stipulated accommodating the various requirements of DSO. Accordingly, the trading setups and processes of the FLECH market are also illustrated in detail.A quantitative example is utilized to illustrate the formulation and classification of flexibility services provided by the DERs in the proposed FLECH market.