### Clue: Treat casually opinion US President held about another last in office (4,3,7)
### Answer: TAKE FOR GRANTED 
 ### Explanation: Definition: Treat casually
 TAKE(one's opinion, as is "what's your take on the Brexit referendum?") + FORD(Gerald, former US President) **containing**(held about) [ GRANT(Ulysses S., another former US President) + **the last letter of**(last in) "office "].