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' shows that the letters should be reversed in order (letters go back or 'ebb').
'tide' becomes 'sea' (I have seen 'The tide' mean 'sea' so perhaps 'tide' could also mean 'sea').
'sea' in reverse letter order is 'aes'.
'gi' inserted within '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" .)