### Clue: Get in the head to teach — not standard! (5)
### Answer: LEARN 
 ### Explanation: Definition: Get in the head
A sort of double definition – to "get something in your head" is to learn it, and "learn" is a non-standard word for "teach", as in "that'll learn you!" I say "sort of" because the two meanings are really of the same word used in two related ways