Get ready to show part of body (7)
I believe the answer is:
forearm
I believe this is a double definition.
'get ready' is the first definition.
(to arm in advance)
'part of body' is the second definition.
(I've seen this before)
'to show' acts as a link.
(Other definitions for forearm that I've seen before include "prepare defence in advance" , "where is the radius?" , "Prepare to defend" , "Attention" , "Limb part; prepare" .)