May be burning to help out the college head! (4)
I believe the answer is:
acid
'may be burning' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'help out the college head' is the wordplay.
'help' becomes 'aid' (synonyms).
'out' is an insertion indicator.
'the college head' becomes 'c' (I've seen this in other clues).
'aid' going around 'c' is 'ACID'.
'to' is the link.
Can you help me to learn more?
(Other definitions for acid that I've seen before include "Sour - sharp" , "Sarcastic (could be sulphuric?)" , "Sour - LSD" , "It is neutralized by alkali" , "Corrosive fluid" .)