Rosemary perhaps, the female bishop (4)
I believe the answer is:
herb
'rosemary perhaps' is the definition.
(rosemary is a kind of herb)
'the female bishop' is the wordplay.
'the female' becomes 'her' (I've seen this before).
'bishop' becomes 'b' (abbreviation used in chess).
'her'+'b'='HERB'
(Other definitions for herb that I've seen before include "Eg, sage" , "Useful or edible plant" , "Plant used in cooking" , "Rosemary perhaps" , "Wayside plant with small red flowers" .)