Composer that is welcomed by King sees extravagant light fitting (10)
I believe the answer is:
chandelier
'extravagant light fitting' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'composer that is welcomed by king sees' is the wordplay.
'composer' becomes 'handel' (George Frideric Handel).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'welcomed by' means one lot of letters goes inside another (letters welcomed inside).
'king sees' becomes 'cr' (I can't explain this - if you can you should give a lot more credence to this answer).
'handel'+'ie'='handelie'
'handelie' inserted into 'cr' is 'CHANDELIER'.
Can you help me to learn more?
(Other definitions for chandelier that I've seen before include "lights up?" , "Ornament" , "Hanging light fixture" , "Ornamental light fitting" , "Ornamental lighting fixture" .)