Limited containment of bug (4)
I believe the answer is:
mite
'bug' is the definition.
(thesaurus)
'limited containment of' is the wordplay.
'containment of' indicates a hidden word.
'MITE' is hidden in the letters of 'limited'.
(Other definitions for mite that I've seen before include "Child; a small amount" , "Very small creature or child" , "The widow's small offering" , "Tiny arachnid, person or amount of money" , "The widow's small donation" .)