Strange gap in Nell’s wall surfacing (9)

I believe the answer is:

panelling

I'm a little stuck... Click here to teach me more about this clue!

'wall surfacing' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?

'strange gap in nell's' is the wordplay.
'strange' is an anagram indicator.
'gap'+'in'+'nell'='gapinnell'
'gapinnell' is an anagram of 'PANELLING'.

Can you help me to learn more?

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app