Tirade on socialist dog is something fruity (3,7)

'something fruity' is the definition.
(type of fruit)

'tirade on socialist dog' is the wordplay.
'tirade' becomes 'rant' (both can mean an angry outburst).
'on' says to put letters next to each other.
'socialist' becomes 'red' (socialism is often associated with the colour red).
'dog' becomes 'cur' (both can mean a despicable person).
'red'+'cur'='redcur'
'rant' after 'redcur' is 'RED CURRANT'.

'is' is the link.