Shifting to centre, politicians clash (11)
I believe the answer is:
contretemps
'clash' is the definition.
(I know that contretemps is a type of clash)
'shifting to centre politicians' is the wordplay.
'shifting' indicates an anagram.
'politicians' becomes 'MPs' (Members of Parliament).
'to'+'centre'='tocentre'
'tocentre' anagrammed gives 'contrete'.
'contrete'+'mps'='CONTRETEMPS'
(Other definitions for contretemps that I've seen before include "Minor disagreement" , "Awkward argument" , "Awkward clash" , "Inopportune happening" , "Unexpected embarrassment" .)