Hammering is read as force used to shape, fix or drive a point home. Dream books see it as determination, or as anger looking for a useful form.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.