Upset when denied entry with locks (7)
I believe the answer is:
tressed
'with locks' is the definition.
(locks and tresses can both mean hair)
'upset when denied entry' is the wordplay.
'upset' becomes 'stressed'.
'when denied entry' means to remove the first letter (the opening or entrance to the word is removed).
'stressed' with its first letter removed is 'TRESSED'.
(Other definitions for tressed that I've seen before include "Having locks" , "(Of hair) braided" .)