For the most part, full beam replaced with a torch (8)
I believe the answer is:
flambeau
'torch' is the definition.
(I know that flambeau is a type of torch)
'for the most part full beam replaced with a' is the wordplay.
'for the most part' means to remove the last letter (most but not all of the letters).
'replaced with' is an anagram indicator.
'full' with its final letter taken off is 'ful'.
'ful'+'beam'='fulbeam'
'fulbeam' anagrammed with 'a' can make 'FLAMBEAU'.
(Other definitions for flambeau that I've seen before include "One may be burning" , "Flaming torch" , "Burning torch" , "Old blazer" , "Torch; candlestick" .)