It's a grave honour to get these flowers (6)
I believe the answer is:
wreath
'grave honour to get these flowers' is the definition.
The definition suggests an adverb but the answer is not.
'it's a' is the wordplay.
I cannot really understand how this works, but
'a' is within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
The remaining letters 'wreh' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for wreath that I've seen before include "26 Down may be shaped into this decorative ring" , "Circular garland" , "Funeral arrangement" , "Circle of flowers used at funerals" , "Flower arrangement" .)