Hi Manilaboy,
Here i have a solution for u to achieve what u want.
Plz go to back end , geodirectory > Place(Custom post) setting > Custom fields tab and then expand Special offer field by clicking on that row, scroll down and see the section to enter custom css for this field (see attached image). Enter a unique name for this custom fields, e.g. geodir_(custom_post_type)_fieldname, so if u have special offer field for places post type then class name can be ‘geodir_place_special_offer’, put this name in css class[text field] and save this setting.
Now plz add below code in your design > scripts > custom css section to hide that field.
.geodir-sidebar-wrap .geodir_place_special_offer{display:none;}
You can do this with other custom fields too in other post types.
Please let me know if it works for you, i am always here to assist u further.
Thanks