Watch over bishop making deal (6)
I believe the answer is:
timber
'deal' is the definition.
(I've seen this before)
'watch over bishop' is the wordplay.
'watch' becomes 'timer' (a watch might be used to time something).
'over' indicates putting letters inside.
'bishop' becomes 'B' (abbreviation for bishop in chess).
'timer' enclosing 'b' is 'TIMBER'.
'making' is the link.
(Other definitions for timber that I've seen before include "board" , "Mind the falling tree!" , "Sawn wood" , "Ash perhaps" , "Warning cry that a tree is about to fall" .)