Python: Making bowling algorithm more pythonic
Overall, there is not much sense in using a class here - you are not using player's name and you are calculating the overall shots in the frames method and returning the overall value.

Some code style specific notes:


according to PEP8, the class name should be in CamelCase, call it BowlingPlayer
there is no need for parenthesis around the expressions, you can replace:

self.overall += (shot_three_after_strike + shot_two_after_strike + shot_one)


with:

self.overall += shot_three_after_strike + shot_two_after_strike + shot_one

there is some code duplication when you calculate the overall value, you can add up shot_two_after_strike and shot_one to the overall value and only if the score is 10, add the shot_three_after_strike:

self.overall += shot_two_after_strike + shot_one
if shot_two_after_strike == 10: # you got another strike. continue the frame!
    shot_three_after_strike = int(input('how many pins on shot after two strikes:'))
    self.overall += shot_three_after_strike
return self.overall


Same for the case when shot_one &lt; 10.
according to PEP8 commenting guidelines, there has to be two spaces before the # and once space after
there is no need for spaces around the = for keyword function or method arguments (PEP8 reference)
put the main execution code to under if __name__ == '__main__': to avoid it being executed on import
let's define 10 as a constant to avoid hardcoding things
I'd also use something like a total_points variable name instead of a more questionable overall


Improved code:

POINTS_FOR_STRIKE = 10


class BowlingPlayer(object):
    def __init__(self, name, overall=0):
        self.name = name
        self.total_points = overall

    def frames(self):
        shot_one = int(input('how many pins on first shot:'))
        if shot_one == POINTS_FOR_STRIKE:  # this is a strike
            shot_two_after_strike = int(input('how many pins on shot after strike:'))
            self.total_points += shot_two_after_strike + shot_one

            if shot_two_after_strike == POINTS_FOR_STRIKE:  # you got another strike. continue the frame!
                shot_three_after_strike = int(input('how many pins on shot after two strikes:'))
                self.total_points += shot_three_after_strike
        elif shot_one &lt; POINTS_FOR_STRIKE:
            shot_two = int(input('how many pins on second shot:'))
            shots = shot_one + shot_two
            self.total_points += shots

            if shots == POINTS_FOR_STRIKE:  # this is a spare
                shot_three_after_spare = int(input('how many pins on shot after spare'))  
                self.total_points += shot_three_after_spare
        return self.total_points


if __name__ == '__main__':
    craig = BowlingPlayer('craig')
    print(craig.frames())