To configure which parts of speech should be included in the word search results, go to Options > Sources > Search rules and check the parts of speech you want to include. Unchecked parts of speech will be ignored. The example below tells pycrossword to include only nouns and verbs:
Fig. 3.9.5.1. Configuring included parts of speech
These settings will of course only be valid if your word sources contain part-of-speech data. Refer to Sections 3.9 and 3.9.1 for details on parts of speech.