Talk a lot about Republican growth (6)
I believe the answer is:
sprout
'growth' is the definition.
(I've seen this before)
'talk a lot about republican' is the wordplay.
'talk a lot' becomes 'spout' (as in spouting off on a topic).
'about' is an insertion indicator.
'republican' becomes 'r' (abbreviation).
'spout' enclosing 'r' is 'SPROUT'.
(Other definitions for sprout that I've seen before include "Burgeon" , "Grow; vegetable" , "Suddenly grow" , "Small cabbage from Brussels?" , "Young shoot" .)