The cad is out to break the engagement (6)
I believe the answer is:
detach
'break the engagement' is the definition.
'detach' can be an answer for 'break' (thesaurus). I am not certain of the 'the engagement' bit.
'the cad is out' is the wordplay.
'is out' is an anagram indicator (out can mean wrong or inaccurate).
'the'+'cad'='thecad'
'thecad' with letters rearranged gives 'DETACH'.
'to' is the link.
Can you help me to learn more?
(Other definitions for detach that I've seen before include "The reverse of 11 Down" , "Separate, disconnect" , "Disengage (something) and remove it" , "Split off" , "free" .)