European married revolutionary American in novel (4)
I believe the answer is:
emma
'novel' is the definition.
(I've seen this before)
'european married revolutionary american' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'married' becomes 'm'.
'revolutionary' is a reversal indicator.
'american' becomes 'am' (abbreviation in some contexts).
'am' in reverse letter order is 'ma'.
'e'+'m'+'ma'='EMMA'
'in' is the link.
(Other definitions for emma that I've seen before include "Best Actress Oscar winner 1992, for 'Howard's End'" , "book" , "companion for Nelson" , "Victorian prime minister" , "Lady Hamilton or Lady Thompson?" .)