Somehow restyle around opening of chamber behind closed doors (8)
I believe the answer is:
secretly
'behind closed doors' is the definition.
(I've seen this before)
'somehow restyle around opening of chamber' is the wordplay.
'somehow' indicates anagramming the letters.
'around' means one lot of letters goes inside another.
'opening of' says to take the initial letters.
The initial letter of 'chamber' is 'c'.
'restyle' with letters rearranged gives 'seretly'.
'seretly' placed around 'c' is 'SECRETLY'.
(Other definitions for secretly that I've seen before include "in disguise?" , "Undercover" , "in camera" , "On the quiet" , "in confidence" .)