Answer:
If it weren't for that glorious third eyebrow on his forehead, I wouldn't have deemed him a handsome man.
Step-by-step explanation:
A complex sentence contains a subordinate clause! In the sentence I have written for you above, if it weren't for that glorious third eyebrow on his forehead is the subordinate clause! It added some info to the whole sentence, but cannot stand as a complete one on its own.