Learn to play on an organ (5)
I believe the answer is:
renal
'on an organ' is the definition.
(renal means relating to the liver)
'learn to play' is the wordplay.
'to play' indicates an anagram.
'learn' with letters rearranged gives 'RENAL'.
(Other definitions for renal that I've seen before include "Learn (anag) - of organs of the body" , "around the kidney" , "Relating to kidneys" , "Concerned with organ" , "like kidneys" .)