Clue: Number Two is getting cut off projects involving horse (5,3,5)
Answer: TWIST AND SHOUT
Explanation: Definition: Number

**TWI**(n) ("two" getting cut off) + **STANDS OUT** ("projects") *involving* **H** (horse)
 

 
*Number = song*
 

 
*Not entirely sure of my parsing here, as "twin" and "two" as synonyms may be pushing it a bit (I was thinking of things like "Twin Towers")?