Announcement of giant squeeze (7)
I believe the answer is:
tighten
'squeeze' is the definition.
(tighten can mean to squeeze or contract)
'announcement of giant' is the wordplay.
'announcement of' indicates a 'sounds like' (homophone) clue.
'giant' becomes 'titan' (titans are giant mythological creatures).
'titan' sounds like 'TIGHTEN'.
(Other definitions for tighten that I've seen before include "Turn, a screw say" , "increase tension" , "contract" , "Apply increased tension or security" , "Make harder to undo" .)