The move returns the Birmingham-based firm to the discipline it has built its reputation on for more than 54 years.
Clancy said the change would strengthen its ability to support clients across the built environment and position it for long-term growth.
The decision to step away from Building Services follows a period of challenging market conditions and skills pressures in that sector, resulting in a number of redundancies.
Where possible, affected staff will transition to another consultancy to help maintain continuity for clients.
Chris Acton, chief executive of Clancy Consulting, said: "These essential changes mark the next chapter for Clancy. By returning our full focus to Civil and Structural Engineering, we're building on the expertise and reputation that have defined our business for more than five decades.
"We're creating a business with greater clarity, greater focus and an even stronger platform for our future. Our clients will continue to receive the same high-quality service they know and trust, while we focus on the capabilities that will shape the future of our practice."
The Civil and Structural Engineering business will continue to be led by its existing board director team.
Clancy's current portfolio includes the delivery of a new sustainable community at Adelphi Village in Salford, a 20-year nationwide partnership with Holcim, and a long-standing collaboration with North Ayrshire Council on public sector projects across the region.
