Upstanding lecturer gives assent (3)
I believe the answer is:
nod
'assent' is the definition.
(I've seen this in another clue)
'upstanding lecturer' is the wordplay.
'upstanding' says the letters should be written backwards.
'lecturer' becomes 'don' (don can mean an academic).
'don' written backwards gives 'NOD'.
'gives' acts as a link.
(Other definitions for nod that I've seen before include "Show recognition" , "Cain was banished to the land of ..." , "Indicate assent; make slip" , "Be agreeably" , "'A . . . is as good as a wink to a blind horse'" .)