Compact bag the smallest article fills (4)
I believe the answer is:
neat
'compact' is the definition.
(I've seen this before)
'bag the smallest article fills' is the wordplay.
'bag' becomes 'net' (I've seen this in other clues).
'the smallest article' becomes 'a' (the indefinite article in English. I am not sure about the 'smallest' bit.).
'fills' means one lot of letters goes inside another (one set of letters goes inside another).
'net' placed around 'a' is 'NEAT'.
Can you help me to learn more?
(Other definitions for neat that I've seen before include "(Of alcohol) not diluted" , "bull, eg" , "compact" , "Alcoholic drink without a mixer" , "Straight - cool!" .)