//includes
...

typedef struct ITEM
{
   int it_id;
   BMAP* it_bmap;
} ITEM;

ITEM* item_001 = malloc(sizeof(ITEM));
   item_001.it_id = 001;
   item_001.it_id = "item_001.png";

give_item()
{
   pan_inventory_slot.bmap = item_001.bmap;
}

void main()
{
   //Level and Game initalizing
   ...
   
   on_t = give_item;
}

typedef struct ITEM
{
   int it_id;
   BMAP* it_bmap;
} ITEM;

ITEM item_001; //No malloc needed, if you want to keep it, then keep it.. (dont forget malloc returns a POINTER)
item_001.it_id = 1;
item_001.it_bmap = bmap_create("item_001.png");

function give_item(ITEM *pItem)
{
   pan_inventory_slot.bmap = pItem.bmap;
}

void main()
{
   //Level and Game initalizing
   ...
   
   give_item(&item_001);
}

ITEM item_001;

function main()
{
     ...

     item_001.it_id = 1;
     item_001.it_bmap = bmap_create("item_001.png");

     give_item(&item_001);
}