Sorry agent upset tenant (9)
I believe the answer is:
repentant
'sorry' is the definition.
(similar in meaning)
'agent upset tenant' is the wordplay.
'agent' becomes 'rep' (short for representative).
'upset' indicates an anagram.
'tenant' with letters rearranged gives 'entant'.
'rep'+'entant'='REPENTANT'
(Other definitions for repentant that I've seen before include "sorry state" , "Contrite" , "Regretful" , "showing contrition" , "Feeling remorse for misdeeds" .)