Sex coming up in wedding photos perhaps results in fighting between partners? (7,3)
I believe the answer is:
martial art
'sex' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for martial art that I've seen before include "combative sport" , "for which war paint could be used?" , "As a form of self-defence" , "Combat technique" , "the construction of epigrams?" .)