Calm down crazy fool of Conservative initially (4,3)
I believe the answer is:
cool off
'calm down' is the definition.
('cool off' can be a synonym of 'calm down')
'crazy fool of conservative initially' is the wordplay.
'crazy' indicates an anagram.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'initially' says to put letters next to each other.
'fool'+'of'='foolof'
'foolof' with letters rearranged gives 'ooloff'.
'ooloff' after 'c' is 'COOL OFF'.
(Other definitions for cool off that I've seen before include "grow less passionate" , "calm down" , "simmer down" .)