Raised first of readings on sin (3)
I believe the answer is:
err
'sin' is the definition.
(to sin is to err morally)
'raised first of readings on' is the wordplay.
'raised' says the letters should be written backwards (going up in a down clue).
'first of readings' becomes 'r' (1st letter of 'readings').
'on' becomes 're' ('on' can be mean 'with reference to').
'r'+'re'='rre'
'rre' backwards is 'ERR'.
(Other definitions for err that I've seen before include "Transgress" , "Go astray" , "Miss the mark" , "Be mistaken" , "Deviate" .)