Joint: some pork needed (4)
I believe the answer is:
knee
'joint' is the definition.
(I know that knee is a type of hinge joint)
'some pork needed' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'KNEE' can be found hidden inside 'pork needed'.
(Other definitions for knee that I've seen before include "middle part of leg" , "for going on begging" , "Capped joint?" , "Leg hinge" , "It jerks reactively" .)