It’s a shame about termination of sincere expression of holiness (5)
I believe the answer is:
piety
'expression of holiness' is the definition.
'it's a shame about termination of sincere' is the wordplay.
'it's a shame' becomes 'pity' (both are expressions of regret or sorrow).
'about' indicates putting letters inside.
'termination of' suggests the final letters (back).
The final letter of 'sincere' is 'e'.
'pity' going around 'e' is 'PIETY'.
(Other definitions for piety that I've seen before include "Godly behaviour" , "Being faithful" , "Quality of being religious" , "Dutiful devotion" , "Reverence for a god" .)