What does the cryptic crossword clue "Labour movement's endless reproach about Murdoch? (8)" mean?

The wordplay uses a deletion. IRIS (synonym="=Murdoch, i.e. the Irish writer") in BLAM (synonym="BLAM") = BLAIRISM The answer is BLAIRISM.

Labour movement's endless reproach about Murdoch? (8)

Independent Cryptic #11893 | 1 Down | 2024-11-21 flower