Learner in house left Mark outside (7)
I believe the answer is:
'learner' is the definition.
(I know that learner can be written as scholar)
'house left mark outside' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'left' becomes 'L' (common abbreviation).
'mark' becomes 'scar' (mark left by an injury).
'outside' means one lot of letters goes inside another.
'hol' inserted into 'scar' is 'SCHOLAR'.
'in' acts as a link.
(Other definitions for scholar that I've seen before include "university type?" , "Noted academic" , "Man of letters" , "Subject of poem by 1 across" , "Academic, schoolboy" .)