Operate on best kitchen surface (7)
I believe the answer is:
worktop
'kitchen surface' is the definition.
(I've seen this before)
'operate on best' is the wordplay.
'operate' becomes 'work' ('work' can be a synonym of 'operate'**).
'on' is a charade indicator (letters next to each other).
'best' becomes 'top' ('top' can be similar in meaning to 'best').
'work'+'top'='WORKTOP'
(Other definitions for worktop that I've seen before include "Kitchen unit surface" , "Surface in kitchen for preparation, etc" , "E.g. kitchen surface" , "Surface on which to toil" , "Practical surface" .)