Boston basketballer, for short (4)
I believe the answer is:
celt
'boston basketballer for short' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for celt that I've seen before include "Pre-Roman inhabitant of Ireland and Britain" , "one who spoke Manx, for example" , "Early Briton" , "Early European" , "Ancient Briton" .)