Usual problem in clay pit (7)
I believe the answer is:
typical
'usual' is the definition.
(thesaurus)
'problem in clay pit' is the wordplay.
'problem in' indicates anagramming the letters (a faulty or problematic ordering of the letters).
'clay'+'pit'='claypit'
'claypit' anagrammed gives 'TYPICAL'.
(Other definitions for typical that I've seen before include "Stock" , "Characteristic of a particular person or thing" , "Having the essential characteristics of a group" , "Representative or quintessential" , "Representative of a class" .)