It's above the wrist or possibly below (5)
I believe the answer is:
elbow
'it's above the wrist' is the definition.
I can't tell whether this defines the answer.
'possibly below' is the wordplay.
'possibly' is an anagram indicator.
'below' is an anagram of 'ELBOW'.
'or' is the link.
Can you help me to learn more?
(Other definitions for elbow that I've seen before include "Sort of grease" , "Arm joint, more power to it" , "sack?" , "Nudging joint?" , "Below (anag.)" .)