Reason I pass; lecturer reflecting on college (5)
I believe the answer is:
logic
'reason' is the definition.
(logic is using reason)
'i pass lecturer reflecting on college' is the wordplay.
'pass' becomes 'go' (synonyms).
'lecturer' becomes 'l' (abbreviation for lecturer).
'reflecting' is a reversal indicator.
'on' is a charade indicator (letters next to each other).
'college' becomes 'c'.
'go'+'l'='gol'
'gol' written backwards gives 'log'.
'i' put after 'log' is 'logi'.
'logi'+'c'='LOGIC'
(Other definitions for logic that I've seen before include "Reasoned thinking" , "Rigorous reasoning" , "Reasoned argument" , "Rational thinking" , "4-ing" .)