Former legislation is precise (5)
I believe the answer is:
exact
'precise' is the definition.
(I know that precise can be written as exact)
'former legislation' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'legislation' becomes 'act' (I've seen this in other clues).
'ex'+'act'='EXACT'
'is' is the link.
(Other definitions for exact that I've seen before include "Demand, extort" , "Spot-on" , "accurate in all details" , "19 [WREST]" , "Absolutely right" .)