Somehow learn of the kidneys (5)
I believe the answer is:
renal
'of the kidneys' is the definition.
(I've seen this before)
'somehow learn' is the wordplay.
'somehow' indicates an anagram.
'learn' anagrammed gives 'RENAL'.
(Other definitions for renal that I've seen before include "Pertaining to the kidney" , "Pertaining to the kidneys" , "Learn (anag) - of organs of the body" , "around the kidney" , "Referring to organ" .)