Sculpt exterior with writing (4)
I believe the answer is:
text
'writing' is the definition.
(text is a kind of writing)
'sculpt exterior with' is the wordplay.
'with' indicates the answer is hidden within the clue.
'TEXT' can be found hidden inside 'sculpt exterior'.
(Other definitions for text that I've seen before include "Writing or printing" , "inspiration for sermon" , "Written material for study" , "piece of writing" , "Words of a book" .)