Forces sweetheart to get married after love subdued (8)
I believe the answer is:
overawed
'subdued' is the definition.
(I've seen this before)
'forces sweetheart to get married after love' is the wordplay.
'forces sweetheart' becomes 'vera' (Vera Lynn was the 'forces' sweetheart' in WW2).
'to get married' becomes 'wed' ('wed' can be a synonym of 'get married').
'after' is a charade indicator (letters next to each other).
'love' becomes 'o' (love means zero in tennis).
'vera'+'wed'='verawed'
'verawed' put after 'o' is 'OVERAWED'.
(Other definitions for overawed that I've seen before include "Overcome with wonderment" , "Filled with wonder" , "subdued" , "Overwhelmed by a feeling of wonder" , "Overcome with wonder" .)