Show filth around middle of deck (6)
I believe the answer is:
direct
'show' is the definition.
(I've seen this before)
'filth around middle of deck' is the wordplay.
'filth' becomes 'dirt' (synonyms).
'around' indicates putting letters inside.
'middle of' means to look at the middle letters.
The central letters of 'deck' are 'ec'.
'dirt' going around 'ec' is 'DIRECT'.
(Other definitions for direct that I've seen before include "Straight and to the point" , "'Straight, without deviation (6)'" , "Order; straight" , "Supervise; unambiguous" , "Frank; undeviating" .)