He has his own ideas on hoarding (10)
I believe the answer is:
advertiser
'his own ideas on hoarding' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he' is the wordplay.
I cannot really understand how this works, but
'he' could be 'ad' and 'ad' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'has' acts as a link.
Can you help me to learn more?
(Other definitions for advertiser that I've seen before include "He pushes" , "who does the plugging" , "Publicist" , "commercial employee" , "Commercial producer" .)