An outright boon, this element? (5)
I believe the answer is:
boron
'an outright boon this element?' is the definition.
'boron' can be an answer for 'element?' (boron is a kind of element). I'm not certain of the remainder of the definition.
'boon this element?' is the wordplay.
'boon' becomes 'boro' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'this element?' becomes 'N' (N is an example).
'boro'+'n'='BORON'
Can you help me to learn more?
(Other definitions for boron that I've seen before include "Non-metallic element, symbol B" , "Atomic no 5" , "element needed for steel" , "Metalloid element, B" , "Chemical element, symbol B" .)