Discussion of great intellectuals becomes more stringent (8)
I believe the answer is:
tightens
'more stringent' is the definition.
(I've seen this before)
'discussion of great intellectuals' is the wordplay.
'discussion of' indicates a 'sounds like' (homophone) clue.
'great intellectuals' becomes 'titans' (titan can mean a very notable person in a field).
'titans' is a homophone of 'TIGHTENS'.
'becomes' is the link.
(Other definitions for tightens that I've seen before include "more stringent" , "Increases restrictions" .)