Ship-shape joints (4)
I believe the answer is:
hips
'joints' is the definition.
(hip is a kind of joint)
'ship-shape' is the wordplay.
'shape' is an anagram indicator.
'ship' is an anagram of 'HIPS'.
(Other definitions for hips that I've seen before include "Cheers" , "Haunches" , "Fruit of a rose plant" .)