Field can modify by Approval Person only

Summary:

How can we restrict the filed access to specific level only

Content (required):

We have configured worksheet approval hierarchy at three level, now when worksheet is populated then % and amount value are auto populated based on Grade wise % policy defined under UDT.

Compensation Manger : Now Compensation manager will see the worksheet and pass his comment and submit for the approval but he cannot modify the Allocated % or Amount.

Update only done by Approval Person : now who is receive approval notification he can able to update the field.

Can we archive this.

Version (include the version you are using, if applicable):