Place at an angle to the main alignment (6)
I believe the answer is:
offset
'place at an angle to the main alignment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for offset that I've seen before include "Distance out of line" , "Place out of line" , "Compensation; printing technique" , "Place at an angle to the main alignment" , "make an effort" .)