### Clue: Bug and grub in part of plant (7)
### Answer: TAPROOT 
 ### Explanation: Definition: part of plant
 TAP(to bug;to eavesdrop on a telephone communication with a concealed device, that's also known as a bug) **plus**(and) ROOT(to grub;to dig in the earth).
Defn: … that grows straight down from the stem into the ground.