That of a sea rover may have a ring in it (3)
I believe the answer is:
ear
'that of a sea rover' is the definition.
I can't judge whether this defines the answer.
'have a ring in it' is the wordplay.
'in it' indicates the answer is hidden within the clue (I've seen this in other clues).
'EAR' is hidden within 'have a ring'.
'may' acts as a link.
Can you help me to learn more?
(Other definitions for ear that I've seen before include "good sense of music" , "willingness to listen" , "A corny bit" , "Organ inside heart" , "organ with drum" .)