Security on the borders checks procedures (7)
I believe the answer is:
systems
'procedures' is the definition.
(I've seen this in another clue)
'security on the borders checks' is the wordplay.
'on the borders' suggests removing the centre (the edge/border letters).
'checks' becomes 'stems' (check can mean to stem or stop).
'security' with its middle removed is 'sy'.
'sy'+'stems'='SYSTEMS'
(Other definitions for systems that I've seen before include "ways of proceeding" , "Theories of universe, perhaps" , "procedures" , "Arrangements of units that function together" , "that all go before lift-off?" .)