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 "Mixture for soaking meat before cooking", "Steep in seasoning", "Mixtures used for soaking foods before cooking", "In a dream (anag.)", "Mixture for soaking foods before cooking", "Flavouring liquid found in a dream", "Soak food before cooking", "Liquid for soaking food before cooking", "Spicy liquid for soaking meat or fish" and "Spiced liquid in which food is soaked before cooking".)