Fellow to get married (3)
I believe the answer is:
tom
'fellow' is the definition.
(man's name)
'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 "Boy - cat" , "A male domestic cat" , "Edgar's Poor disguise (Lear)" , "What Dick Whittington had" , "Man's name; male cat" .)