Learn layout of the kidneys (5)
I believe the answer is:
renal
'of the kidneys' is the definition.
(renal means relating to the kidneys)
'learn layout' is the wordplay.
'layout' indicates an anagram (an alternative layout of the letters).
'learn' with letters rearranged gives 'RENAL'.
(Other definitions for renal that I've seen before include "Like an organ" , "Referring to organ" , "Concerned with organ" , "using the reins" , "like kidneys" .)