She will shortly show a hard exterior (5)
I believe the answer is:
shell
'a hard exterior' is the definition.
'shell' can be an answer for 'exterior' (thesaurus). I'm not certain of the 'a hard' bit.
'she will shortly' is the wordplay.
'she' becomes 'shel' ().
'shortly' suggests the final letters.
The final letter of 'will' is 'l'.
'shel'+'l'='SHELL'
'show' is the link.
Can you help me to learn more?
(Other definitions for shell that I've seen before include "A little pasta" , "layer of jacket" , "Hull" , "Walls of gutted building" , "magazine article" .)