Additional part of text, racy (5)
I believe the answer is:
extra
'additional' is the definition.
(I know that additional can be written as extra)
'part of text racy' is the wordplay.
'part of' indicates a hidden word.
'EXTRA' is hidden within 'text racy'.
(Other definitions for extra that I've seen before include "Minor player in film" , "Ancillary" , "to boot" , "Additional - bye" , "Minor actor in crowd scene" .)