THEME:   one letter of a phrase is changed to U   
GOOD ONES:     Flea?   DOGGIE BUG [doggie bag]   
Prospector's close attachment to his helper?   MULE BONDING [male bonding]   
Reservation for an upper berth?   BUNK DEPOSIT [bank deposit]   
Corkers?   IRISH [I thought comedians, not those from Cork]   
Blood line   VEIN   
Follower of directions?   ERN [as in western or northern]   
First name in architecture   EERO [both ways]   
Confirmation, e.g.   RITE   
Cell user   PRISONER   
Subway selection   ONION [I thought trains, but BMT was too short]   
Where to find stories on Friday?   DRAGNET [TV's Joe Friday]   
Fresh bean sprout?   IDEA [bean = head]   
Driving need?   TEE   
Pitchers may hold them   ICED TEAS [I thought baseballs]   
Season opener?   ESS      
BTW:   I believe this puzzle has set the all-time record for clever entries.      
My newspaper had the title "You Must be Joking," but I wonder if it was supposed to be "U Must be Joking."      
Dull thing to be in   A RUT [used to be forbidden to use the indefinite article in an answer that didn't need it]      
1970 Poitier title role   TIBBS ["They call me 
Mister Tibbs!"]      
ELHI in the real world is "K-12," which I guess sounds like a spot remover.  Elhi sounds like a biblical name.      
Is down with   HAS [as in "has the flu"; hipsters might use it to mean "has no objection"]      
Macbeth's burial site   IONA [the real Mac
Beth died there; I believe Shakespeare's Mac
beth died at Scone at Malcom's hand]      
RATING:    
 
  
 
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun