### Clue: Heart-breaking period in a small measure (10)
### Answer: CENTIMETRE 
 ### Explanation: Heart-breaking period in a small measure (10)
**CENTRE** ("heart") with **TIME** ("period") *breaking* 
This one doesn't work for ma, as I read the clue as suggesting that CENTRE should be breaking TIME, rather than the other way round required for the solution to work.