Plant ice axe initially under murder victim (6)
I believe the answer is:
abelia
'plant' is the definition.
(abelia is a kind of plant)
'ice axe initially under murder victim' is the wordplay.
'initially' indicates taking the first letters.
'under' is a charade indicator (letters next to each other).
'murder victim' becomes 'abel' (Biblical character).
The initial letters of 'ice axe' is 'ia'.
'ia' after 'abel' is 'ABELIA'.
(Other definitions for abelia that I've seen before include "Honeysuckle" , "shrub" , "plant" .)