This page agrees that it is the badge of the 1st Hussar Regiment of Estonia, http://militaria19191938.org/2018/06/05/3-original-estonian-1920-era-military-badges-silver-estonian-1st-hussar-regimt/ The one shown on the page linked to was made in Estonia, though. Here is an Estonian Wikipedia page about the regiment which shows an illustration of the badge and if you Google "Ratsarügement" you will find lots more on the regiment and its badge.