If it helps, do the title in the old fashioned way: capitalised.
Specifically within sociology, Define and Explain with some Historical Insight the Concept of Illness using its Relationship to Class.
Applying Rule 1? Break it up:
You'd need the general concept of illness that cannot be separated from the sociological stance.
But this needs to be defined and explained. The definition and explanation, it is noted, relates to class. This focuses the definition away from other sociological strata.
This suggests a new order, conceptually:
1) The Concept of Illness
2) Specifically within Sociology
3) Define and Explain
4) with some Historical Insight
5) using its Relationship to Class