A school for instruction with power these days took me back first year (7)
I believe the answer is:
academy
'a school' is the definition.
(I know that academy is a type of school)
'power these days took me back first year' is the wordplay.
'power' becomes 'ac' (AC is an example).
'these days' becomes 'AD' (as in Anno Domini, after Christ).
'took' says to put letters next to each other.
'back' shows that the letters should be reversed in order.
'first' suggests taking the first letters.
The initial letter of 'year' is 'y'.
'me' back-to-front is 'em'.
'ac'+'ad'+'em'+'y'='ACADEMY'
'for instruction with' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for academy that I've seen before include "Institution for the advancement of the arts and sciences" , "Institution for the advancement of art, science, literature" , "training centre" , "institute" , "Learning institution" .)