Pitch in when encountering Conservative policy (7)
I believe the answer is:
incline
'pitch' is the definition.
('incline' can be a synonym of 'pitch')
'in when encountering conservative policy' is the wordplay.
'when encountering' means one lot of letters go next to another.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'policy' becomes 'line' (I've seen this before).
'in'+'c'+'line'='INCLINE'
(Other definitions for incline that I've seen before include "Gradient" , "bow" , "Lean (towards)" , "Have a tendency to do or be something" , "tip" .)