US guy’s way of working when attending school (5)
I believe the answer is:
schmo
'attending school' is the definition.
The definition suggests a singular noun which matches the answer.
'us guy's way of working' is the wordplay.
'us guy' becomes 'sch' (I can't explain this - if you can you should give a lot more credence to this answer).
'way of working' becomes 'mo' (abbreviation for modus operandi).
'sch'+'mo'='SCHMO'
'when' is the link.
Can you help me to learn more?
(Other definitions for schmo that I've seen before include "jerk" , "Boring American" , "Fool (Yiddish)" , "Inept person (US_informal)" , "clot" .)