Stone Age love dismissed by books (7)
I believe the answer is:
peridot
'stone' is the definition.
(type of precious stone)
'age love dismissed by books' is the wordplay.
'age' becomes 'period'.
'love' becomes 'o' (love means zero in tennis).
'dismissed by' suggests deleting specific letters.
'books' becomes 'ot' (Old Testament).
'period' with 'o' removed is 'perid'.
'perid'+'ot'='PERIDOT'
(Other definitions for peridot that I've seen before include "olivine" , "Gemstone -- pre-do it (anag)" , "I deport (anag) - gemstone" , "Pale green gemstone" , "Top ride (anag) - gemstone" .)