Caught up with a sailor's second wife, Bones (9)
I believe the answer is:
metatarsi
'bones' is the definition.
(I've seen this before)
'caught up with a sailor's second wife' is the wordplay.
'caught up with' becomes 'met' (I've seen this in another clue).
'sailor's' becomes 'tar's' (slang term for a sailor).
'second wife' becomes 'i' (2nd letter of 'wife').
'met'+'a'+'tars'+'i'='METATARSI'
(Other definitions for metatarsi that I've seen before include "bones" , "Parts of the feet" .)