Standing among three rectors (5)
I believe the answer is:
erect
'standing' is the definition.
(similar in meaning)
'among three rectors' is the wordplay.
'among' indicates the answer is hidden within the clue.
'ERECT' is hidden within 'three rectors'.
(Other definitions for erect that I've seen before include "Upright or vertical" , "Build, upright" , "Construct, build" , "Unbowed" , "Build - straight up" .)