Less common for Republicans to accept age reversal (5)
I believe the answer is:
rarer
'less common' is the definition.
('rare' can be the opposite of 'common' so perhaps 'rarer' is reasonable for 'less common')
'republicans to accept age reversal' is the wordplay.
'republicans' becomes 'rr' (I can't explain this - if you can you should believe this answer much more).
'to accept' means one lot of letters goes inside another.
'age' becomes 'era' (both can mean a long time).
'reversal' shows that the letters should be reversed in order.
'rr' placed around 'era' is 'rerar'.
'rerar' in reverse letter order is 'RARER'.
'for' is the link.
Can you help me to learn more?
(Other definitions for rarer that I've seen before include "Less frequent" , "Comparatively sparse" , "steak may be wanted thus?" , "Less often seen" , "(Of meat) less cooked" .)