Bonjour Hilary
In response to your request, I think that the village that you search is VILLARS LE SEC, département: Territoire-de-Belfort (90), région: Franche-Comté.
Before 1870 the Territoire-de-Belfort was a part of the Haut-Rhin (68) also of Alsace. Between 1870 and 1918 Alsace became German but the Territoire-de-Belfort remained French and is still département since 1922 with its own Archives Départementales.
I did not find other information on your family CLERGET or LOISET.
Try
www.lisa90.org and
www.cegfc.net and send them your request. Or write to the town hall of Villars le sec: Mairie de Villars le sec, 8 RUE PRINCIPALE,
90100 VILLARS LE SEC, FRANCE.
Salutations
Michel Ittel