Record set by one Conservative making sense (5)
I believe the answer is:
logic
'sense' is the definition.
(logic is a kind of sense)
'record set by one conservative' is the wordplay.
'record' becomes 'log' (log is a kind of record).
'set by' says to put letters next to each other.
'one' becomes 'I' (Roman numeral).
'conservative' becomes 'C' (UK political abbreviation).
'log'+'i'+'c'='LOGIC'
'making' acts as a link.
(Other definitions for logic that I've seen before include "Strict reasoning" , "Branch of philosophy that analyses inference" , "Chain of reasoning" , "Dialectics" , "Reasoned judgement" .)