See about US university working for a small interval (8)
I believe the answer is:
semitone
'a small interval' is the definition.
(interval between two musical notes)
'see about us university working' is the wordplay.
'about' means one lot of letters goes inside another.
'us university' becomes 'MIT' (Massachusetts Institute of Technology).
'working' becomes 'on'.
'mit'+'on'='miton'
'see' placed around 'miton' is 'SEMITONE'.
'for' acts as a link.
(Other definitions for semitone that I've seen before include "Interval between adjacent keys, on a piano say" , "Small interval between notes" , "Short musical interval" , "100 cents" , "Small musical interval" .)