Plant found in that room occasionally (4)
I believe the answer is:
taro
'plant' is the definition.
(taro is a kind of plant)
'that room occasionally' is the wordplay.
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'that'+'room'='thatroom'
The alternate letters of 'thatroom' are 'TARO'.
'found in' is the link.
(Other definitions for taro that I've seen before include "Chinese eddo" , "Root to eat" , "A rot turns the lily-like plant" , "Shortly pack" , "Starchy plant" .)