As mentioned by OctaveL, in the function create you try to set the fields of the queue but the pointer passed to the function does not point to a queue, it is uninitialized. If you add the option -Wall to gcc it will actually warn you about this:

$ gcc -o test -Wall test.c
test.c: In function 'main':
test.c:71:5: warning: 'q' is used uninitialized in this function [-Wuninitialized]
     create (q);
     ^~~~~~~~~~

Solution 1: Declare q as a record and pass the address of q to the function create:

struct queue q;
create (&q);

Solution 2: Declare q as a pointer and allocate a new queue variable:

struct queue *q;
q = malloc(sizeof *q);
create(q);

I would also advice you to rename the function create to init or clear since it doesn't create a new queue, it only initializes (or clears) it.

To make memory allocation easier and to handle errors properly it is convenient to introduce two macros:

#define NEW_ARRAY(ptr, n) \
    (ptr) = malloc((n) * sizeof (ptr)[0]); \
    if ((ptr) == NULL) { \
        fprintf(stderr, "Memory allocation failed: %s\n", strerror(errno)); \
        exit(EXIT_FAILURE); \
    }

#define NEW(ptr) NEW_ARRAY(ptr, 1)

With these in place and if create is renamed to init you can write solution 2 as

struct queue *q;
NEW(q);
init(q);