''.join and start:stop:step notation for lists

[BashBedlam]

You were close... Try it like this:

phrase = "Don't panic!"
plist = list(phrase)
 
plist.remove("'")
plist.insert(6,plist.pop(3))
new_phrase = ''.join(plist[1:4] + plist[-5:-8:-1])

print(new_phrase)