### Clue: Change of direction in match (5)
### Answer: RIGHT 
 ### Explanation: "r"(abbrev. for the direction "right") **replacing**(Change of direction …) "l"(abbrev. for the direction "left") ***in ***"light"( a device to produce a flame/a match) .
Answer: As in a "right-angled triangle", one with an angle of 90 degrees.