What canines have lair and can dine without noise? (7)
I believe the answer is:
dentine
'what canines have' is the definition.
(tissue forming teeth eg canines)
'lair and can dine without noise?' is the wordplay.
'lair' becomes 'den' (synonyms).
'and' means one lot of letters go next to another.
'can' becomes 'tin' (synonyms).
'without' indicates named letters should be taken away.
'noise?' becomes 'din' (din can mean a loud noise or disturbance).
'dine' with 'din' taken out is 'e'.
'den'+'tin'+'e'='DENTINE'
(Other definitions for dentine that I've seen before include "Substance of which teeth are mainly composed" , "Tooth material" , "which forms tooth" , "Material in teeth" , "bony material" .)