The right are right less often (5)
I believe the answer is:
'the' is the definition.
I can't tell whether this defines the answer.
'right are right less often' is the wordplay.
'right' becomes 'r' (common abbreviation).
'are right' becomes 'ar' (I've seen this in other clues).
'less often' becomes 'er' (I can't justify this - if you can you should believe this answer much more).
Can you help me to learn more?
(Other definitions for rarer that I've seen before include "More unusual" , "steak may be wanted thus?" , "More scarce or uncommon" , "even less common" , "Less often seen" .)