Egg on show, sandwiching in order (7)
I believe the answer is:
provoke
'egg on' is the definition.
(thesaurus)
'show sandwiching in order' is the wordplay.
'show' becomes 'prove' (synonyms).
'sandwiching' indicates putting letters inside (to sandwich can mean to contain or block in).
'in order' becomes 'OK' (both can mean acceptable or appropriate).
'prove' going around 'ok' is 'PROVOKE'.
(Other definitions for provoke that I've seen before include "needle" , "Affront" , "Deliberately annoy" , "Incite to anger" , "Make angry or incite to action" .)