Loved to fuss over the socialist (6)
I believe the answer is:
adored
'loved' is the definition.
(adoring is a kind of loving)
'fuss over the socialist' is the wordplay.
'fuss' becomes 'ado' (synonyms).
'over' says to put letters next to each other.
'the socialist' becomes 'red' (red is a kind of socialist).
'ado'+'red'='ADORED'
'to' is the link.
(Other definitions for adored that I've seen before include "Much loved" , "Loved, venerated" , "Loved intensely" , "Worshipped and venerated" , "Loved dearly" .)