Ascent of Conservative member (5)
I believe the answer is:
climb
'ascent' is the definition.
(I know that ascent can be written as climb)
'conservative member' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'member' becomes 'limb' (member can mean a limb).
'c'+'limb'='CLIMB'
'of' acts as a link.
(Other definitions for climb that I've seen before include "Use hands and feet to rise" , "What mountaineer does" , "Get higher" , "Scale or clamber" , "Slope upwards" .)