Real excited about small ray (5)
I believe the answer is:
laser
'ray' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'real excited about small' is the wordplay.
'excited' indicates an anagram.
'about' means one lot of letters goes inside another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'real' is an anagram of 'laer'.
'laer' going around 's' is 'LASER'.
Can you help me to learn more?
(Other definitions for laser that I've seen before include "Generator of beam" , "Device producing an intense beam of light or radiation" , "Device that produces an intense beam of light" , "Beam (used in surgery)" , "Device yielding powerful beam" .)