Project detail (4)
I believe the answer is:
spec
'project detail' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for spec that I've seen before include "Estimate" , "Detailed design document (abbr.)" , "Detailed design (colloq.)" , "on which chance is taken" , "Gamble (colloq.)" .)