Gift posted again under pressure (7)
I believe the answer is:
present
'gift' is the definition.
('present' can be a synonym of 'gift')
'posted again under pressure' is the wordplay.
'posted again' becomes 'resent' ('sent' can be a synonym for 'posted' so perhaps 'resent' is OK for 'posted again').
'under' says to put letters next to each other.
'pressure' becomes 'p' (abbreviation).
'resent' after 'p' is 'PRESENT'.
(Other definitions for present that I've seen before include "Gift; time now; here" , "able to be registered" , "Introduce < and compere < tense" , "Introduce formally" , "available" .)