Seaman, then another seaman cut ankle bone? (6)
I believe the answer is:
tarsal
'ankle bone?' is the definition.
(I've seen this in another clue)
'seaman then another seaman cut' is the wordplay.
'seaman' becomes 'tar' (Jack Tar is an informal term for a sailor).
'then another seaman cut' becomes 'sal' (I can't justify this - if you can you should give a lot more credence to this answer).
'tar'+'sal'='TARSAL'
Can you help me to learn more?
(Other definitions for tarsal that I've seen before include "Of the bones making up the foot" , "One of the seven ankle bones" , "Foot bone" , "To do with bones of upper foot" .)