import re


def clear_sent(sent):
    """Remove all non-letters symbols, except `-`

    Args:
        sent (str): Sentence

    Returns:
        str: Cleared sentence
    """
    sent = re.sub(r'[^-\w]+', ' ', sent)
    sent = re.sub(r'(\s-\s*|-\s+)', ' ', sent)
    return sent.strip()