Chum getting married gets a bit of a hand (4)
I believe the answer is:
palm
'a bit of a hand' is the definition.
('palm' is part of 'hand')
'chum getting married' is the wordplay.
'chum' becomes 'pal' ('pal' can be a synonym of 'chum').
'getting' means one lot of letters go next to another.
'married' becomes 'm'.
'pal'+'m'='PALM'
'gets' is the link.
(Other definitions for palm that I've seen before include "Secretly snatch" , "may need greasing" , "Symbol of victory" , "Tree with no branches and large leaves" , "Leaf in part of the hand?" .)