Contract is put together, restricted by this writer’s impracticality (8)
I believe the answer is:
idealism
'impracticality' is the definition.
(idealism is a kind of impracticality)
'contract is put together restricted by this writer's' is the wordplay.
'contract' becomes 'deal' (I've seen this before**).
'put together' means one lot of letters go next to another.
'restricted by' is an insertion indicator (I've seen this in other clues).
'this writer's' becomes 'im' (the person writing the crossword clues).
'deal'+'is'='dealis'
'dealis' inserted inside 'im' is 'IDEALISM'.
(Other definitions for idealism that I've seen before include "Pursuit of the perfect" , "Noble attitude from miladies" , "Utopian pursuit" , "The pursuit of perfection" , "Aspirations to good things for miladies" .)