Century before capital gains tax finally ending (6)
I believe the answer is:
climax
'ending' is the definition.
(I know that climax is a type of consummation)
'century before capital gains tax finally' is the wordplay.
'century' becomes 'C' (common abbreviation).
'before' says to put letters next to each other.
'capital' becomes 'lima' (capital of Peru).
'gains' is a charade indicator (letters next to each other).
'finally' suggests the final letters.
The final letter of 'tax' is 'x'.
'c'+'lima'+'x'='CLIMAX'
(Other definitions for climax that I've seen before include "Turning point or culmination" , "Peak of emotion" , "Most exciting point" , "Culminating moment" , "Highest point" .)