I think you can just put it into a list, and then concat the list. In Pandas, the chunk function kind of already does this. I personally do this when using the chunk function in pandas.
pdList = [df1, df2, ...] # List of your dataframes
new_df = pd.concat(pdList)
To create the pdList automatically assuming your dfs always start with “cluster”.
pdList = []
pdList.extend(value for name, value in locals().items() if name.startswith('cluster_'))