THEME:   the letter W written with two U's   
GOOD ONES:     Letter that hints how 18 answers…   DOUBLE U   
Conference, informally   
POUUUUOUU [powwow]   
Duo   
TUUO [two, and I always thought it should be "tuo" rather than 
duo]   
One way to get a hand   ANTE [I thought applause]   
Modern crime head?   CYBER ["head" meaning "lead-in"]   
Bolt with great speed   USAIN [the great runner]      
BTW:   It must've taken me an hour to complete this --- half of which before I got to the last entry.      
Suit at a shoot   BIKINI [I was sure I was right with ARMANI, especially since I thought I was right with PATHS rather than PIERS]      
Leather craftperson's beltful   AUULS [for AWLS, but leather workers work at benches so don't wear belts --- and I love the non-sexist 
person rather than 
man --- of course 
person is also sexist because it ends in 
son, not 
daughter: solution is to change 
person to "perone"]      
Neither 
SUPE nor
 TROU is a word, and while I see that the difficulty of construction may qualify these letter combination, I feel it weakens the puzzle a bit.         
RATING: 
 
  
  
   Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun