Medicine enabling you to turn in with a cool head? (5)
I believe the answer is:
tonic
'medicine enabling you' is the definition.
'tonic' can be an answer for 'medicine' (I've seen this before). I'm unsure of the 'enabling you' bit.
'turn in with a cool head?' is the wordplay.
'turn in' says the letters should be written backwards.
'with' indicates putting letters inside.
'a cool' becomes 'in' ('in' can mean fashionable or cool).
'head?' becomes 'cot' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' placed inside 'cot' is 'cinot'.
'cinot' backwards is 'TONIC'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for tonic that I've seen before include "something nice and fresh" , "Small drink of spirits" , "Quinine water" , "A pick-me-up drink, nice with gin" , "Gin mixer - pick-me-up" .)