Seal hollow bath aperture? (8)
I believe the answer is:
plughole
'bath aperture?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'seal hollow' is the wordplay.
'seal' becomes 'plug' (I've seen this before).
'hollow' becomes 'hole' (synonyms).
'plug'+'hole'='PLUGHOLE'
Can you help me to learn more?
(Other definitions for plughole that I've seen before include "What's designed for draining" , "It can be stopped" , "outlet" , "Bath drain" .)