Small trendy quiet mimic, neat (9)
I believe the answer is:
shipshape
'neat' is the definition.
(synonyms)
'small trendy quiet mimic' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'trendy' becomes 'hip' (I've seen this before).
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'mimic' becomes 'ape' (ape can mean to copy or imitate).
's'+'hip'+'sh'+'ape'='SHIPSHAPE'
(Other definitions for shipshape that I've seen before include "Hash pipes may be in good order - like sailor?" , "In good order, like well-dressed sailor?" , "Exhibiting neatness" , "In seaworthy condition" , "Neat and trim" .)