Representation of power in speech gripping board (9)
I believe the answer is:
portrayal
'representation' is the definition.
(I know that portrayal is a type of pictorial representation)
'power in speech gripping board' is the wordplay.
'power' becomes 'p' (symbol in physics).
'in speech' becomes 'oral' (oral means relating to speech).
'gripping' is an insertion indicator (inserted letters are gripped).
'board' becomes 'tray'.
'oral' going around 'tray' is 'ortrayal'.
'p'+'ortrayal'='PORTRAYAL'
'of' acts as a link.
(Other definitions for portrayal that I've seen before include "Study" , "painting" , "Depicting characters" , "Picture or description of royal prat" , "It depicts" .)