As long as I understood your question correctly, this should work.
IF(AND({ITEM DESCRIPTION},{TASK TYPE}, {TASK NAME}), CONCATENATE({ITEM DESCRIPTION}," - ",{TASK TYPE},": ",{TASK NAME}),IF(AND({ITEM DESCRIPTION},{TASK TYPE}), CONCATENATE({ITEM DESCRIPTION}, " - ",{TASK TYPE}), {ITEM DESCRIPTION}))
Hey @Scott_Gardner1!
Assuming you are always going to have a value in the Item Description field, this formula should work for you:
IF(
{ITEM DESCRIPTION},
{ITEM DESCRIPTION} & IF(
{TASK TYPE},
" - " & {TASK TYPE}
) & IF(
{TASK NAME},
": " & {TASK NAME}
)
)

This formula, as shown above, will not return anything if there is not an Item Description, to begin with.
If you want to display the rest of the values regardless of whether or not the Item Description is provided, then you can use this structure instead:
IF(
{ITEM DESCRIPTION},
{ITEM DESCRIPTION} & IF(
{TASK TYPE},
" - " & {TASK TYPE}
) & IF(
{TASK NAME},
": " & {TASK NAME}
),
IF(
OR(
{TASK NAME},
{TASK TYPE}
),
IF(
{TASK TYPE},
{TASK TYPE} & IF(
{TASK NAME},
": " & {TASK NAME}
),
IF(
{TASK NAME},
{TASK NAME}
)
)
)
)
That formula will return this behavior:

Edit:
Changed the field names to be capitalized like your example.