Complex sentence: Tosh's overall assessment is that a shift is needed in conceptualizing the topic back to the history of masculinity as a speciality aiming to reach a broader audience, rather than as an analytical tool of cultural and social history.
Split into simpler sentences: Tosh's overall assessment is that a shift is needed in conceptualizing the topic. This needs to take the form of a move back to the history of masculinity being a specialism in its own right with an aim to reach a broader audience rather than to simply be an analytical tool in cultural and social history.