Wide orifice, gross (5)
I believe the answer is:
whole
'gross' is the definition.
(thesaurus)
'wide orifice' is the wordplay.
'wide' becomes 'w' (abbreviation e.g. in cricket).
'orifice' becomes 'hole' (I've seen this in another clue).
'w'+'hole'='WHOLE'
(Other definitions for whole that I've seen before include "In entirety" , "Total" , "Complete, containing all the parts" , "All the components" , "Entire, undivided" .)