Faithful concerned with good man consumed by hypocrisy (8)
I believe the answer is:
constant
'faithful' is the definition.
('constant' can be similar in meaning to 'faithful')
'concerned with good man consumed by hypocrisy' is the wordplay.
'concerned with' becomes 'on' (I've seen this in other clues).
'good man' becomes 'st'.
'consumed by' means one lot of letters goes inside another.
'hypocrisy' becomes 'cant' (I've seen this before).
'on'+'st'='onst'
'onst' going within 'cant' is 'CONSTANT'.
(Other definitions for constant that I've seen before include "Changeless and unceasing" , "Continuing unvarying" , "Persistent and unchanging" , "Unwavering" , "Steady and unceasing" .)