Bury dog, perhaps, assuming relatives initially understand (9)
I believe the answer is:
interpret
'understand' is the definition.
(I know that interpret is a kind of the understand)
'bury dog perhaps assuming relatives initially' is the wordplay.
'bury' becomes 'inter' (to inter is to put into the ground).
'dog perhaps' becomes 'pet' (dogs are often kept as pets).
'assuming' is an insertion indicator (inserted letters are taken in or assumed).
'initially' suggests taking the first letters.
The first letter of 'relatives' is 'r'.
'pet' enclosing 'r' is 'pret'.
'inter'+'pret'='INTERPRET'
(Other definitions for interpret that I've seen before include "Restate from one language into another" , "Assign one's own meaning to" , "Discern the meaning of" , "Construe" , "Read" .)