Terrace queen found in royal museum (7)
I believe the answer is:
veranda
'terrace' is the definition.
(I've seen this before)
'queen found in royal museum' is the wordplay.
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'found in' indicates putting letters inside.
'royal museum' becomes 'vanda' (Victoria and Albert Museum. I am not sure about the 'royal' bit.).
'er' inserted into 'vanda' is 'VERANDA'.
Can you help me to learn more?
(Other definitions for veranda that I've seen before include "Porch - portico" , "Open roofed platform" , "Part of house roofed" , "Ground-floor extension" , "Roofed platform level with the ground floor" .)