Top stone surrounding hearth (7)
I believe the answer is:
singlet
'top' is the definition.
(I've seen this before)
'stone surrounding hearth' is the wordplay.
'stone' becomes 'st'.
'surrounding' indicates putting letters inside.
'hearth' becomes 'ingle' (I've seen this before).
'st' enclosing 'ingle' is 'SINGLET'.
(Other definitions for singlet that I've seen before include "Sleeveless vest" , "top gear" , "Tingles in vest" , "garment worn by men" , "Underwear" .)