Any number intruding can be a nuisance (5)
I believe the answer is:
annoy
'be a nuisance' is the definition.
(I've seen this before)
'any number intruding' is the wordplay.
I cannot really understand how this works, but
'number' could be 'no' (abbreviation for 'number') and 'no' is found within the answer.
The remaining letters 'any' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'can' acts as a link.
Can you help me to learn more?
(Other definitions for annoy that I've seen before include "Gall" , "Vex" , "Displease" , "Irritate, needle" , "Irritate - pester" .)