In a way age is some protection (5)
I believe the answer is:
aegis
'some protection' is the definition.
('aegis' can be a synonym of 'protection')
'in a way age is' is the wordplay.
'in a way' indicates anagramming the letters.
'age' with letters rearranged gives 'aeg'.
'aeg'+'is'='AEGIS'
(Other definitions for aegis that I've seen before include "Protection, backing" , "shelter" , "Protection - guardianship" , "strong defence" , "Protection (originally a shield)" .)