Without notice, serviceman's in a pickle (8)
I believe the answer is:
Here is my best explanation:
'a pickle' is the definition.
'without notice serviceman's' is the subsidiary indication.
'without' means one lot of letters goes inside another.
'notice' becomes 'ad'.
'serviceman' becomes 'marine' (marine is a kind of serviceman**).
'ad' going within 'marine' is 'marinade'.
'in' is the link.
(Other definitions for marinade that I've seen before include "souse", "Soak in a mixture before cooking", "steep?", "Soak food before cooking", "Cooking liquid", "pickle", "Mixture for soaking foods before cooking", "spicy sauce", "Liquid for soaking food before cooking" and "Mixture for soaking meat before cooking".)