Ducks out of mounting charity events around university (5)
I believe the answer is:
sugar
'ducks' is the definition.
(both are terms of endearment)
'mounting charity events around university' is the wordplay.
'mounting' is a reversal indicator (going up in a down clue).
'charity events' becomes 'rags' (rag can mean a university charity event).
'around' indicates putting letters inside.
'university' becomes 'u' (abbreviation for university).
'rags' enclosing 'u' is 'ragus'.
'ragus' in reverse letter order is 'SUGAR'.
'out of' acts as a link.
(Other definitions for sugar that I've seen before include "Make more palatable" , "--- Ray Robinson, boxer" , "White or brown sweetener" , "Sweet ingredient" , "Basic sweetener" .)