Casanova secured buckles (7)
I believe the answer is:
seducer
'casanova' is the definition.
(I've seen this before)
'secured buckles' is the wordplay.
'buckles' indicates an anagram.
'secured' anagrammed gives 'SEDUCER'.
(Other definitions for seducer that I've seen before include "Casanova, for example" , "Philanderer" , "Rescued by sexual tempter" , "Wolf" , "Don Juan" .)