Trunk roughly attached to elephant at last (5)
I believe the answer is:
torso
'trunk' is the definition.
('torso' can be a synonym of 'trunk')
'roughly attached to elephant at last' is the wordplay.
'roughly' becomes 'orso' ('or so' can be a synonym of 'roughly'**).
'attached to' says to put letters next to each other.
'at last' indicates one should take the final letters.
The final letter of 'elephant' is 't'.
'orso' after 't' is 'TORSO'.
(Other definitions for torso that I've seen before include "Poorly-dressed child" , "unfinished work" , "Body's core" , "part of body will be found" , "Roost on trunk?" .)