Doing model's work, apropos in nice clothes (6)

I believe the answer is:
posing
'doing' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'model's work apropos in nice clothes' is the wordplay.
I cannot quite understand how this works, but
'in' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for posing that I've seen before include "About to be shot, perhaps" , "putting on an act" , "Assuming a certain position" , "puzzling" , "Putting forward" .)
