Beetle up a stick (3)
I believe the answer is:
rod
'a stick' is the definition.
(I've seen this before)
'beetle up' is the wordplay.
'beetle' becomes 'dor' (I've seen this in another clue).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'dor' back-to-front is 'ROD'.
(Other definitions for rod that I've seen before include "Flexible stick for 11 Down" , "Angler's equipment" , "Straight, slender stick" , "Instrument of punishment" , "Cane - shaft" .)