The effect, on one politician, of a piece of legislation? (6)
I believe the answer is:
impact
'the effect' is the definition.
(impact is a kind of effect)
'one politician of a piece of legislation?' is the wordplay.
'one politician of' becomes 'imp' (I can't justify this - if you can you should give a lot more credence to this answer).
'a piece of legislation?' becomes 'act' (I've seen this in another clue).
'imp'+'act'='IMPACT'
'on' is the link.
Can you help me to learn more?
(Other definitions for impact that I've seen before include "Significance" , "Forcible contact; marked influence" , "hit, in a big way" , "The force fo violent strike" , "Collision - effect" .)