Free a sailor put inside when violent (5)
I believe the answer is:
rabid
'violent' is the definition.
(I've seen this in another clue)
'free a sailor put inside' is the wordplay.
'free' becomes 'rid' (to be free of something is to be rid of it).
'a sailor' becomes 'ab' (abbreviation for able seaman).
'put inside' means one lot of letters goes inside another.
'rid' placed around 'ab' is 'RABID'.
'when' is the link.
(Other definitions for rabid that I've seen before include "Zealous" , "Ill from a mad dog bite?" , "Affected by 24 across" , "Wild" , "Fanatical like mad dog" .)