Possible Title:
In Other WordsGood Ones:Amount past due? TRE [if you happen to know Italian]
Theme: Common phrases reinterpreted
Litter in an abandoned library? LEAVESINTHEDUST
Bread seen while finding theater seats? ROLLINTHEAISLE
Imaginary nuclear facility? PLANTINONESMIND
By the Way:I enjoyed the wide range of subject matter. As an example, take the 5-Across area: AQUA {color}; SURF {sports idiom}; ASSISI {religious history}; QUID {foreign exchange}; URN {mundane appliance}; AFT {marine terminology}. One has to know religious history as well as surfing jargon.
Some Nits to Pick:Irreversibly committed INDEEP [“In deep” does not suggest irreversibility. The idiom suggests being involved, but not such that one is “in too deep.”]
It’s quarry HIDERS [Quarry only sometimes hides. Would tweeters, fliers, runners also define “quarry?” Maybe I’m missing something --- like why the clue needs "It's."]
RATING:

Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun