The fourth terrible Tory row about European retreat (5,5)
I believe the answer is:
ivory tower
'retreat' is the definition.
(I've seen this in another clue)
'the fourth terrible tory row about european' is the wordplay.
'the fourth' becomes 'iv' (Roman numerals for four).
'terrible' indicates anagramming the letters.
'about' says to put letters next to each other.
'european' becomes 'E' (abbreviation e.g. EU).
'tory'+'row'='toryrow'
'toryrow' after 'e' is 'etoryrow'.
'etoryrow' with letters rearranged gives 'orytower'.
'iv'+'orytower'='IVORY TOWER'
(Other definitions for ivory tower that I've seen before include "Academia (seen as secluded)" , "State of seclusion from worldly realities" , "Seclusion from ordinary life" , "academic position" .)