Clue: Dwarf planet absorbing odd bits of meteor mass — astronaut's opening tinned food? (4,6)
Answer: PLUM TOMATO
Explanation: Definition: tinned food?

**PLUTO** ("dwarf planet") *absorbing* [*odd bits of*] **M**(e)**T**(e)**O**(r) + **M** (mass) + **A**(stronaut) [*'s opening*]