import re

chosen_word = "to crank (sth) up"
# To make the space between words double for better legibility
hidden_word = re.sub("\s", "  ", chosen_word)

# To hide the letters of the word 
hidden_word = re.sub(r"(\bto\b|\(s(?:th|b)\))|[a-z]", lambda x: x.group(1) or "_ ", hidden_word)
print( hidden_word )