Irritation when summit is announced (5)
I believe the answer is:
pique
'irritation' is the definition.
(I know that irritation can be written as pique)
'summit is announced' is the wordplay.
'summit' becomes 'peak' (mountain peak).
'is announced' shows a homophone (sound like).
'peak' sounds like 'PIQUE'.
'when' acts as a link.
(Other definitions for pique that I've seen before include "Equip (anag.)" , "Animosity" , "Slight reaction" , "Feeling of wounded pride" , "A feeling of hurt pride" .)