### Clue: Circle date for invading and finding capacity (9)
### Answer: BANDWIDTH 
 ### Explanation: Definition: capacity
 BAND(a circular piece of material) + { D(abbrev. for "date") **contained in**(for invading) WITH(and;together) }.
Defn: … of an electronic communication channel, in terms of the amount of data that can be passed along it in a given period of time.