Mapmaker almost happy with intervention of censor (8)
I believe the answer is:
mercator
'mapmaker' is the definition.
(I've seen this before)
'almost happy with intervention of censor' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'happy' becomes 'merry'.
'with intervention of' means one lot of letters goes inside another.
'censor' becomes 'Cato' (ancient Roman censor).
'merry' with its final letter removed is 'merr'.
'merr' going around 'cato' is 'MERCATOR'.
(Other definitions for mercator that I've seen before include "Flemish geographer and cartographer" , "Projector" , "was famous for projection" , "Deviser of projection" , "Projectionist" .)