Clustering should indeed return groups of items, in your case persons.
If you are interested in groups of similar features, and you have a small number of features I recommend the you'll compute the correlation among them. There are many correlation measures and you should choose the proper one according to your goals. Common correlations are mutual information, Pearson correlation and covariance. That will give you the correlation between pairs of features. Usually you can manually scan the list and see which features are close.
A more complicated tehcnique is to use your data set of person and build a dataset of presons' features. The items will be age, weight, etc. The distance function will be the correlation measure you choose. Then you run a clustering algorithm on this dataset and get groups of similar feature.
Please note that the typical use of clustering is your case will be to create groups of persons and not feature. If you'll describe more in the comments what you are looking for, maybe the community will be able to offer other methods.