ringfence

/R IH1 NG F AH0 N S/
noun
  1. 1

    A fence which encircles a large area, or a whole estate, within one enclosure.

verb
  1. 1

    To guarantee the safety of funds or investment. In particular, to ensure some degree of distinction for monies, that may provide immunity against untoward financial claims.

  2. 2

    To specify that funds may only be used for a specific purpose, especially government funds.

  3. 3

    To require workers to remain in (particular types of work), as during wartime.

Source: https://en.wiktionary.org/wiki/ringfence