What Tories did for Thatcher's victory over Heath? (5)
I believe the answer is:
voted
'what tories did for thatcher's' is the definition.
'victory over heath?' is the wordplay.
'victory' becomes 'v'.
'over' becomes 'o' (cricket abbreviation).
'heath?' becomes 'ted'.
'v'+'o'+'ted'='VOTED'
(Other definitions for voted that I've seen before include "Expressed preference in a ballot" , "Went to the polls" , "Elected" , "Picked" , "Suggested" .)