Short working party with top base (7)
I believe the answer is:
squalid
'base' is the definition.
(thesaurus)
'short working party with top' is the wordplay.
'short' means to remove the last letter.
'working party' becomes 'squad' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'top' becomes 'lid' (lid is a kind of top).
'squad' with its final letter taken away is 'squa'.
'squa'+'lid'='SQUALID'
(Other definitions for squalid that I've seen before include "run down" , "Slum-like" , "Mean and dirty" , "Seedy" , "Seamy, sleazy" .)