Commercial, six seconds, given to expert, sensible (9)
I believe the answer is:
advisable
'sensible' is the definition.
(similar in meaning)
'commercial six seconds given to expert' is the wordplay.
'commercial' becomes 'ad' (abbreviation for advertisement).
'six' becomes 'VI' (Roman numerals).
'seconds' becomes 's' (abbreviation).
'given to' says to put letters next to each other.
'expert' becomes 'able' (able can mean expert or talented).
'ad'+'vi'+'s'+'able'='ADVISABLE'
(Other definitions for advisable that I've seen before include "Prudent - recommended" , "Wise, recommended" .)