For buffets in the mess, arranged it as the centrepiece (6)
I believe the answer is:
smites
'for buffets in the mess arranged it as the centrepiece' is the definition.
I can't judge whether this definition defines the answer.
'for buffets in the mess arranged' is the wordplay.
'for buffets' becomes 'it' (I am not sure about this - if you are sure you should believe this answer much more).
'in the' is an insertion indicator.
'arranged' indicates anagramming the letters.
'mess' with letters rearranged gives 'smes'.
'it' placed into 'smes' is 'SMITES'.
Can you help me to learn more?
(Other definitions for smites that I've seen before include "biblical hits" , "Strikes heavily or kills, biblical word" , "Deals a heavy blow" .)