### Clue: Showing self-confidence that is largely lightweight (6)
### Answer: BOUNCE 
 ### Explanation: Definition: Showing self-confidence
  Much(*largely*) of the answer is OUNCE(*lightweight*,1/16 of a pound weight).  (I can't otherwise explain the B, and if I'm not wrong, it's a bit of loose clueing.)  The word JOUNCE means the same. 
Defn:  One with,*showing self-confidence* will show bounce in his/her steps.  (A bit uncomfortable with a noun or verb as an answer to an adjectivial definition.)  Also what 1A and 23A do to the ball before serving.