Lunar cycle related to a bone (5)
I believe the answer is:
ulnar
'bone' is the definition.
(I've seen this before)
'lunar cycle related' is the wordplay.
'lunar' anagrams to 'ULNAR'.
Though, I'm unsure how the anagram is indicated.
'to a' acts as a link.
Can you help me to learn more?
(Other definitions for ulnar that I've seen before include "Relating to one of the bones of the forearm" , "of certain bones" , "Relating to a bone in the forearm" , "Relating to a particular arm bone" .)