import re
clean_title = re.match(r'(.*)(.*)', title.lower())
if clean_title:
   return clean_title.group(1).rstrip()

>>'Alone in the Dark (The Cincinnati Series Book 2)'
>>'alone in the dark'

>>> clean_title = 'Alone in the Dark (The Cincinnati Series Book 2)'
>>> clean_title.split('(', 1)[0].lower().rstrip()
'alone in the dark'

>>> clean_title = 'Test'
>>> clean_title.split('(', 1)[0].lower().rstrip()
'test'