Be a recruit in the possibly silent service (6)
I believe the answer is:
enlist
'be a recruit in the' is the definition.
I can't tell whether this definition defines the answer.
'silent service' is the wordplay.
'service' indicates an anagram (I've seen 'serviced' mean this (to service can mean to repair)).
'silent' anagrammed gives 'ENLIST'.
'possibly' is the link.
Can you help me to learn more?
(Other definitions for enlist that I've seen before include "Enrol - recruit" , "Enrol in the services" , "Join the army" , "Join up, sign on" , "Obtain help of" .)