Are there examples of reduplication that clearly changes the syntactic category of a root/stem? I'm thinking of cases like:
pak, n 'tortilla'
pakpak, v 'make tortillas'
tap, a 'red'
tatap, v 'redden'
The language with pervasive reduplication I know best, Kaqchikel (Mayan), has reduplication turning affect words into intransitive verbs, like the following example, but as far as I know, there aren't cases of reduplication that change core syntactic categories.
witz' 'the sound mice make'
niwitz'itz' 'he/she/it made the sound mice make'