Miserly minister snatching this writer’s promissory notes (12)
I believe the answer is:
parsimonious
'miserly' is the definition.
(I've seen this before)
'minister snatching this writer's promissory notes' is the wordplay.
'minister' becomes 'parson' (church minister).
'snatching' is an insertion indicator.
'this writer's' becomes 'I'm' (the person writing the crossword clues).
'promissory notes' becomes 'ious' (IOU is an example).
'parson' placed around 'im' is 'parsimon'.
'parsimon'+'ious'='PARSIMONIOUS'
(Other definitions for parsimonious that I've seen before include "Frugal" , "Cheese-paring" , "Thrifty, mean" , "Penny-pinching" , "Tight-fisted" .)