Sydney University tarnished when kept up thus (9)
I believe the answer is:
sustained
'kept up thus' is the definition.
I can't tell whether this definition defines the answer.
'sydney university tarnished' is the wordplay.
'sydney university' becomes 'su' (this could be a standard abbreviation I've not previously seen).
'tarnished' becomes 'stained' (synonyms).
'su'+'stained'='SUSTAINED'
'when' is the link.
Can you help me to learn more?
(Other definitions for sustained that I've seen before include "Steady" , "bore" , "prolonged" , "Long drawn-out" , "Kept going, supported" .)