Regular place of education favouring maths principally (7)
I believe the answer is:
uniform
'regular' is the definition.
(similar in meaning)
'place of education favouring maths principally' is the wordplay.
'place of education' becomes 'uni' (I am not sure about this - if you are sure you should believe this answer much more).
'favouring' becomes 'for' (to be 'for' something is to be in favour of it).
'principally' indicates taking the first letters.
The first letter of 'maths' is 'm'.
'uni'+'for'+'m'='UNIFORM'
Can you help me to learn more?
(Other definitions for uniform that I've seen before include "what soldier wears?" , "Identical - livery" , "Distinctive clothing worn by a group" , "Official wear; unvarying" , "Unvarying; livery" .)