Something to believe in (5)
'something to believe in' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for credo that I've seen before include "ideology" , "Apostles' beliefs" , "Formal statement of beliefs" , "Guiding beliefs" , "Part of the service" .)
(Other definitions for creed that I've seen before include "Catechism" , "Church doctrine" , "Set of beliefs or principles" , "System of principles or beliefs" , "teleprinter" .)
'something to believe in' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ism that I've seen before include "Any system of beliefs" , "Unspecified doctrine" , "Suffix denoting doctrine or practice" , "form of belief?" , "Distinctive theory" .)