Herb’s two pronouns (5)
I believe the answer is:
thyme
'herb's' is the definition.
(thyme is a kind of herb)
'two pronouns?' is the wordplay.
'two pronouns?' can mean two replacements for 'pronoun'.
'pronoun' becomes 'thy' (historical version of 'your').
'pronoun' becomes 'me' (first-person pronoun).
'thy'+'me'='THYME'
(Other definitions for thyme that I've seen before include "Strong herb" , "Shrubby herb" , "Plant of the mint family" , "Culinary herb of the mint family" , "Small shrub with minty odour" .)