Overturn university marker over delta (5)
I believe the answer is:
upend
'overturn' is the definition.
(to upend is to turn over)
'university marker over delta' is the wordplay.
'university' becomes 'u' (abbreviation for university).
'marker' becomes 'pen' (marker pen).
'over' means one lot of letters go next to another.
'delta' becomes 'd' (phonetic alphabet: alpha, bravo, charlie etc.).
'u'+'pen'+'d'='UPEND'
(Other definitions for upend that I've seen before include "Affect drastically" , "Set upside down" , "Trip" , "Set on side, turn over" , "Turn top to bottom" .)