Should you cluster before performing collaborative filtering?
Short Answer: No, you should not perform clustering before doing matrix factorisation.
First, I just want to say SVD is a special case of Matrix Factorisation. Another thing, SVD in recommendations is not traditional SVD, but has a different form.
Detailed Answer for why (in general) you should not perform clustering before doing matrix factorisation
Matrix Factorisation (MF) itself performs clustering. When you perform Matrix Factorisation, you end up with latent vectors for user and items. By running a clustering algorithm, such as K-Means, on these latent vectors, you end up doing clustering. But, if your end goal is just to recommend, then, there is no point performing clustering apriori.
In some corner cases, you may consider performing clustering

Do you want to cluster to understand the data better and build different recommendation models for every different cluster? If yes, then you may consider doing clustering before hand.