One studying larch so haphazardly (7)
I believe the answer is:
scholar
'one studying' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'larch so haphazardly' is the wordplay.
'haphazardly' is an anagram indicator.
'larch'+'so'='larchso'
'larchso' is an anagram of 'SCHOLAR'.
Can you help me to learn more?
(Other definitions for scholar that I've seen before include "Pupil - erudite person" , "Subject of poem by 1 across" , "Person of learning" , "Academic; pupil" , "Academic, schoolboy" .)