Priory in control, holding on (9)
I believe the answer is:
monastery
'priory' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'control holding on' is the wordplay.
'control' becomes 'mastery' (mastery can mean control or command of something).
'holding' means one lot of letters goes inside another.
'mastery' going around 'on' is 'MONASTERY'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for monastery that I've seen before include "Community of monks" , "Where brothers gather" , "Religious house" , "Religious establishment" , "brother's house" .)