Upright object supporting leg (2,3)
I believe the answer is:
on end
'upright' is the definition.
(thesaurus)
'object supporting leg' is the wordplay.
'object' becomes 'end' (I've seen this in other clues**).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'leg' becomes 'on' (cricket term, fielding positions).
'end' after 'on' is 'ON END'.
(Other definitions for on end that I've seen before include "Upturned, as a box" , "continuing in an upright position" , "Without pause" , "Upright, without cease" , "Continuing without stopping; upright" .)