It's all right to stuff joint of meat - it's a chance to participate (4-2)
I believe the answer is:
look-in
'a chance to participate' is the definition.
(I've seen this before)
'it's all right to stuff joint of meat' is the wordplay.
'it's all right' becomes 'ok' (synonyms).
'to stuff' indicates putting letters inside (some letters stuff into others).
'joint of meat' becomes 'loin' (I've seen this before).
'ok' put into 'loin' is 'LOOK-IN'.
'it's' is the link.
(Other definitions for look-in that I've seen before include "Make a short visit of visual sort?" , "Chance of success" , "Watch TV (colloq.)" .)