Sluggish pig circling pound (4)
I believe the answer is:
slow
'sluggish' is the definition.
('slow' can be similar in meaning to 'sluggish')
'pig circling pound' is the wordplay.
'pig' becomes 'sow' (I've seen this before).
'circling' indicates putting letters inside (circling can mean going around or containing).
'pound' becomes 'l'.
'sow' placed around 'l' is 'SLOW'.
(Other definitions for slow that I've seen before include "Tardy - dull-witted" , "Behind time" , "Owls (anag.)" , "lacking any precipitation" , "Dilatory" .)