Principle of the empty trap (5)
I believe the answer is:
tenet
'principle' is the definition.
(a tenet is a principle or value)
'the empty trap' is the wordplay.
'empty' suggests removing the centre.
'trap' becomes 'net' (net is a type of trap).
'the' with its centre taken out is 'te'.
'te'+'net'='TENET'
'of' acts as a link.
(Other definitions for tenet that I've seen before include "Canon" , "Conviction" , "you may believe in it" , "Teaching" , "It's believed" .)