Not sure if you really want, ':' between DATE and TIME, but if you do not then you can try below -
SELECT CAST(UR_TIMESTAMP_FIELD AS TIMESTAMP FORMAT 'ddmmmyyyyhhmiss')
(Instead of hhmmss - you should try hhmiss)
If you really want ':' between your DATE and TIME, then you have to do CAST it as CHAR or VARCHAR and then SUBSTR DATE and TIME and concatenate (||) them by putting ':' in between.
What is the datatyoe of your input and what should be the resulting datatype?
Char -> timestamp?
Timestamp -> char?
Timestamp -> timestamp?