Snivel about Republican endorsement (5)
I believe the answer is:
blurb
'endorsement' is the definition.
(I know that endorsement can be written as blurb)
'snivel about republican' is the wordplay.
'snivel' becomes 'blub' (I can't explain this - if you can you should give a lot more credence to this answer).
'about' means one lot of letters goes inside another.
'republican' becomes 'r' (abbreviation).
'blub' enclosing 'r' is 'BLURB'.
Can you help me to learn more?
(Other definitions for blurb that I've seen before include "printed on jacket" , "A book's puff" , "Marketing text" , "Publisher's text on book" , "Advertising text" .)