The empty traps show principles (6)
I believe the answer is:
tenets
'principles' is the definition.
(I know this)
'the empty traps' is the wordplay.
'empty' says to hollow out the word (remove centre letters).
'traps' becomes 'nets' (net is a kind of trap).
'the' with its centre removed is 'te'.
'te'+'nets'='TENETS'
'show' acts as a link.
(Other definitions for tenets that I've seen before include "Doctrines of belief" , "Principles of belief" , "Doctrines or dogmas" , "Principles, beliefs" , "'Beliefs, dogmas (6)'" .)