Protection from serviceman in ebbing tide (5)
I believe the answer is:
aegis
'protection' is the definition.
(aegis can mean someone's guidance or protection)
'serviceman in ebbing tide' is the wordplay.
'serviceman' becomes 'gi' (informal term for a US soldier).
'in' is an insertion indicator.
'ebbing' says the letters should be written backwards (to ebb can mean to go backwards).
'tide' becomes 'sea' (I have seen 'The tide' mean 'sea' so perhaps 'tide' could also mean 'sea').
'sea' reversed gives 'aes'.
'gi' put inside 'aes' is 'AEGIS'.
'from' is the link.
(Other definitions for aegis that I've seen before include "Backing or support" , "Protection or sponsorship" , "Kindly endorsement and guidance" , "Protection - patronage" , "Kindly protection" .)