Sailor holding artist's horse (4)
I believe the answer is:
arab
'horse' is the definition.
(Arab is an example)
'sailor holding artist's' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'holding' indicates putting letters inside.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'ab' enclosing 'ra' is 'ARAB'.
(Other definitions for arab that I've seen before include "Saudi, e.g." , "Horse of a breed originating in the Middle East" , "Someone from the Middle East or North Africa, perhaps" , "Semite" , "Small, lively breed of horse" .)