Amusing company -- I'm returning with Conservative (5)
I believe the answer is:
comic
'amusing' is the definition.
(thesaurus)
'company i'm returning with conservative' is the wordplay.
'company' becomes 'co' (abbreviation).
'returning' says the letters should be written in reverse.
'with' is a charade indicator (letters next to each other).
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'im' reversed gives 'mi'.
'co'+'mi'+'c'='COMIC'
(Other definitions for comic that I've seen before include "magazine for kids" , "Stand-up comedian" , "Children's periodical" , "Professional funny person" , "SECOND PART OF 16" .)