Possible Welshman’s skeleton with a different head (5)
I believe the answer is:
jones
'possible welshman's' is the definition.
(common Welsh surname)
'skeleton with a different head' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'one' and 'one' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for jones that I've seen before include "Dad's Army corporal" , "... after which [INDIANA] action hero" , "See 1 Across" , "Inigo -, sixteen to seventeenth century architect" , "Inigo -, Eng. architect" .)