Slice of tomato lying on the floor (3)
I believe the answer is:
mat
'the floor' is the definition.
(thesaurus)
'slice of tomato lying' is the wordplay.
'slice of' indicates the answer is hidden within the clue.
'MAT' can be found hidden inside 'tomato lying'.
'on' is the link.
(Other definitions for mat that I've seen before include "Paint with a dull surface" , "Thick flat pad on the floor" , "Dull, rug" , "Not glossy" , "Rug; without a shine" .)