Popular policy retaining Conservative slant (7)
I believe the answer is:
incline
'slant' is the definition.
(inclining is a kind of slanting)
'popular policy retaining conservative' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'policy' becomes 'line' (I've seen this in another clue).
'retaining' indicates putting letters inside.
'conservative' becomes 'C' (UK political abbreviation).
'in'+'line'='inline'
'inline' placed around 'c' is 'INCLINE'.
(Other definitions for incline that I've seen before include "Lean (towards)" , "Tend; lean" , "Lean, slope" , "bank" , "Tend - slope" .)