Limits of truce probed by border topic (5)
I believe the answer is:
theme
'topic' is the definition.
(I know that topic can be written as theme)
'limits of truce probed by border' is the wordplay.
'limits of' suggests removing the centre.
'probed by' is an insertion indicator (probe can mean to poke or prod into).
'border' becomes 'hem' (I've seen this in another clue).
'truce' with its centre taken out is 'te'.
'te' enclosing 'hem' is 'THEME'.
(Other definitions for theme that I've seen before include "Recurring melody" , "subject,motif" , "Subject matter, motif" , "Topic for discussion" , "Melody on which variations are constructed" .)