Burrowing insect duke removed from flower-bed (5)
I believe the answer is:
borer
'burrowing insect' is the definition.
(insect which bores into wood, rock etc)
'duke removed from flower-bed' is the wordplay.
'duke' becomes 'd'.
'removed from' suggests deleting specific letters.
'flower-bed' becomes 'border' (a flower-bed at a garden's border).
'border' with 'd' removed is 'BORER'.
(Other definitions for borer that I've seen before include "Tunnelling worm or insect" , "Drill" , "Uninteresting type of" , "Destructive worm, mollusc or insect" , "Insect tunnelling into plant" .)