until ATC clear you to a lower level you do not know that it is safe to do so
The entire point of this thread is about whether a clearance to a lower level is implicit in a particular clearance phraseology.
"Cleared ILS" when being vectored is given at a suitable point in the procedure where the flight has been placed correctly by the ATCO on an intercept with the intermediate phase of the approach and is in a position to descend to the level appropriate for the start of that phase (note that it is normally a level phase).
And one can equally argue that:
"Cleared ILS" when on a ATC-initiated direct segment to KELON is given at a suitable point in the procedure where the flight has been placed correctly by the ATCO on to commence the initial phase of the approach from the IAF and is in a position to descend to the level appropriate for the start of that phase.
2. A clearance has a start point and an end. In this case the clearance "cleared ILS Z" while enroute to the IAF ony has effect when the IAF is reached.
So if ATC has cleared me to an on-airfield IAF at 4000 ft above the airport and then uses the phrase "cleared visual approach", do you think that I'm required to fly to the IAF at 4000 ft before commencing descent on the visual approach?
As several posters have pointed out, the safety that you desire comes from clarity about the interpretation that should be placed on particular phraseology. Accidents come from situations where ATC and pilots interpret the same phraseology in different ways
and circumstances prevent a timely clarification.