Are you sure that you have a 45CL-5? It's a model which I've never seen nor heard of before, but it's possible that it is a non-standard custom model number for a specific supplier or territory.
The answer to your question is "possibly": but you asked if it can be used safely so the answer must be a firm "no".
Various sources (e.g. here
) quote the trigger voltage on the (presumably closely related 45CL-4) to be a little higher or even vastly higher than Canon's 6v limit. Metz themselves are unclear on the issue and it doesn't help that they do not list the CL-5 on their support page nor on their main corporate page
, but they do list a 45CL-4 and a 45CL-4 Digital. The differences between the two models may just be to add additional capabilities which suit digital SLR's but perhaps it also brings the trigger voltage below Canon's 6v limit.
As there is so little published information about the 45CL-5 then I strongly suggest that you do not risk your camera until you have a definitive answer from Metz themselves: you can contact their support service by clicking here
. The link is for the UK, if you're elsewhere (Australia?) then you may need to make your own search.
I hope that I've been of some assistance and that the links provided help you to get the answer straight from the horse's mouth. Please take a moment to rate my answer.