He's unlikely to be found out (4-2-4)
I believe the answer is:
stay-at-home
'he's unlikely to be found out' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he's unlikely to be' is the wordplay.
'he's unlikely' becomes 'athome' (I am not sure about this - if you are sure you should believe this answer much more).
'to' means one lot of letters go next to another (I've seen this in other clues).
'be' becomes 'stay' (staying is a kind of being).
'athome' after 'stay' is 'STAY-AT-HOME'.
Can you help me to learn more?
(Other definitions for stay-at-home that I've seen before include "Unadventurous in travel" , "One not given to travel" , "Don't go out" , "Person disinclined to travel" .)