SQL> with
  2  test as
  3    -- sample data
  4    (select '09:30' col from dual union
  5     select '09::30'    from dual union
  6     select 'ab:25'     from dual union
  7     select 'xx/yy'     from dual union
  8     select '55:88'     from dual union
  9     select '22:15'     from dual
 10    ),
 11  time_alike as
 12    -- values that have 2 digits followed by colon (:) followed by 2 digits
 13    (select col
 14     from test
 15     where regexp_like(col, '\d+{2}:\d+{2}')
 16    )
 17  select
 18    -- check whether hours and minutes have sense
 19    col
 20  from time_alike
 21  where to_number(substr(col, 1, 2)) between 0 and 23   -- hours
 22    and to_number(substr(col, -2))   between 0 and 59   -- minutes
 23  /

COL
------
09:30
22:15

SQL>