Crossword puzzle clue "they work with squares"

Opus ___ (Catholic teaching also called "the Work, work work work work")

The squares of "three squares"

They work with squares

Work by Sir Edward Elgar hinted at by this puzzle's circled squares

Poet whose classic work is hidden in this puzzle (see the circled squares of the completed the puzzle)

They're all right in squares

They contrast with squares

They involve mixed feelings ... or a hint to four squares in this completed puzzle