Astonishing start at university (5)
I believe the answer is:
aston
'university' is the definition.
(university in Birmingham)
'astonishing start at' is the wordplay.
I cannot quite see how this works, but
'at' could be 'on' (location) and 'on' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for aston that I've seen before include "Premiership FC" , "- Villa, football club" , "and 20: Midlands football club" , "part of Birmingham" , "A Birmingham university" .)