Cut some lessons, holding out for usual score (3,3,3,6)
I believe the answer is:
par for the course
'usual score' is the definition.
(par is the average score on a golf course)
'cut some lessons holding out' is the wordplay.
'cut some' becomes 'pare' (paring is a kind of cutting. I am not sure about the 'some' bit.).
'lessons' becomes 'course' (a course has lessons).
'holding' means one lot of letters goes inside another.
'out' becomes 'forth' (I've seen this before).
'pare'+'course'='parecourse'
'parecourse' going around 'forth' is 'PAR FOR THE COURSE'.
'for' is the link.
(Other definitions for par for the course that I've seen before include "Typical" , "Normal" , "72?" , "Standard" , "achievement that seems full of holes?" .)