Mother steers one away from this subject (5)
I believe the answer is:
maths
'subject' is the definition.
(I know that maths is a type of science)
'mother steers one away from this' is the wordplay.
'mother steers' becomes 'ma' (I can't explain this - if you can you should believe this answer much more).
'one' becomes 'i' (Roman numeral).
'away from' is a deletion indicator.
'this' with 'i' removed is 'ths'.
'ma'+'ths'='MATHS'
Can you help me to learn more?
(Other definitions for maths that I've seen before include "Numbers subject" , "Adding and subtraction, etc" , "Science dealing with quantity and shapes, in short" , "Algebra, geometry, calculus etc (abbr)" , "Arithmetic etc" .)