THEME: change OL in an odd phrase's word to RE and see a familiar phrase
GOOD ONES: Modernize…and when divided into three parts {theme} RETOOL [literally, RE to OL; though you read it the opposite way: OL to Re]
Hip curriculum? COOL COURSES [change OL to RE = core courses]
Busy enterprise? APIARY ["busy as a bee"]
BTW: "'Tis ture, sorry to say" FRAIDSO [I thought "afraid so" but it didn't fit; then I got THRIFT STOOL and realized, as in the clue, the first vowel is elided. Tough but fair, I think.]
RATING:
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun