Thanks I've read that post before and a couple of others on this movement. Particularly this one https://mb.nawcc.org/threads/welch-verdi-pendulum-assembly.154830/ If you look at the attached pics carefully you can see the brass rod (that I'm calling the crutch) attached to the pendulum rod behind the movement. I'm sure this brass rod attaches to the part I circled previously that you are calling the crutch. I'm new to all the terms so forgive me if I get anything wrong! It's not impossible that the pendulum and rod aren't original to the clock but very unlikely. Clock has been in the family since early 1900s at least possibly longer. Come to think of it though why is the suspension spring mount missing? It's entirely possible one of my ancestors has fiddled with it...
It does make sense that the slot would fit to the part i circled as you suggest but it doesn't and the evidence of the pic I've attached suggests there is another part. If it wasn't for this pic and another I've seen with the brass rod attached the pendulum I'd agree the pendulum rod was the wrong one for the clock.
Take a look at this post, this is a Verdi with a view of the back of the movement and the single piece crutch, which is much longer than the one on your clock, but Welch did make both long and short pendulum drop versions, I suspect on your clock either the pendulum is incorrect or someone as altered the length of the crutch.
I cant see why there would have to be any other part the L shape crutch only has to pass through a slot on the pendulum, are you sure that the pendulum is the correct one for the clock? it looks like someone has tried to alter the slot on the rod at some stage because its pretty chewed up at the back.