Cat to get married (3)
I believe the answer is:
tom
'cat' is the definition.
(a tom is a male cat)
'to get married' is the wordplay.
'get' says to put letters next to each other.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'to'+'m'='TOM'
(Other definitions for tom that I've seen before include "Male feline" , "Pig-stealing piper's son" , "He is associated with Dick and Harry" , "type pursuing queen" , "famous schoolboy" .)