Person is upset because tiresome outsiders used this salutation (7)
I believe the answer is:
namaste
'this salutation' is the definition.
(I've seen this before)
'person is upset because tiresome outsiders' is the wordplay.
'person' becomes 'man' (man is a kind of person).
'is upset' is a reversal indicator (I've seen 'being upset' mean this).
'because' becomes 'as' (I've seen this in other clues).
'outsiders' suggests removing the centre (only the letters on the outside of the word remain).
'tiresome' with its middle removed is 'te'.
'man' backwards is 'nam'.
'nam'+'as'+'te'='NAMASTE'
'used' acts as a link.
(Other definitions for namaste that I've seen before include "salutation" , "sign of respect" , "greeting" .)