Now goes out sailing with the old mariner (3,3)
I believe the answer is:
sea dog
'mariner' is the definition.
(synonyms)
'now goes out sailing with the old' is the wordplay.
I cannot really see how this works, but
'now' could be 'ad' (AD, Anno Domini, as opposed to BC, Before Christ) and 'ad' is found in the answer.
an anagram of 'goes' is 'seog' which is within the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sea dog that I've seen before include "Old or experienced sailor" , "Experienced mariner" , "'Old salt (3,3)'" , "mythical creature" , "Ancient Mariner" .)