Tooth in front of canine is yellow (7)
I believe the answer is:
incisor
'tooth' is the definition.
(incisor is a kind of tooth)
'in front of canine is yellow' is the wordplay.
'front of' says to take the initial letters.
'yellow' becomes 'or' (heraldic term).
The first letter of 'canine' is 'c'.
'in'+'c'+'is'+'or'='INCISOR'
(Other definitions for incisor that I've seen before include "carnivore requires?" , "Canine" , "Narrow-edged tooth" , "oral equipment" , "Type of tooth" .)