Shell company originally needed Switzerland (5)
I believe the answer is:
conch
'shell' is the definition.
(large seashell)
'company originally needed switzerland' is the wordplay.
'company' becomes 'co' (abbreviation).
'originally' says to take the initial letters.
'switzerland' becomes 'ch' (short for Confoederatio Helvetica, its Latin name).
The initial letter of 'needed' is 'n'.
'co'+'n'+'ch'='CONCH'
(Other definitions for conch that I've seen before include "Marine mollusc with a spiral shell" , "Heavy shell" , "Large spiral shell" , "Type of shell" , "Large shell used as trumpet" .)