Paintings of men feature simple frames (11)
I believe the answer is:
portraiture
'paintings of' is the definition.
The definition suggests a singular noun which matches the answer.
'men feature simple frames' is the wordplay.
I cannot really understand how this works, but
'men' could be 'or' (military abbreviation for Other Ranks) and 'or' is found within the answer.
'feature' could be 'trait' (I've seen this in another clue) and 'trait' is found in the answer.
'simple' could be 'pure' (I've seen this in other clues) and 'pure' is present in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for portraiture that I've seen before include "artistry" , "Producing pictures of people" , "perhaps Reynolds'" .)