doubt on CLEAR or REFRESH with FIELDSYMBOLS

hi ,

i wrote code as

loop at <grr_ptr> assigning <grr_ptr1>.

................

...........

clear <grr_ptr1>.

endloop.

when iam saying clear the internal table is getting empty. when i use refresh with <grr_ptr1>, it is saying it is not a workarea.

I have taken both <grr_ptr> and <grr_ptr1> as type any.

how to solve it.