Possibly mean to have the last word (4)
I believe the answer is:
amen
'the last word' is the definition.
(last word in a prayer)
'possibly mean' is the wordplay.
'possibly' indicates an anagram.
'mean' anagrammed gives 'AMEN'.
'to have' is the link.
(Other definitions for amen that I've seen before include "Word of approval" , "Churchgoer's assent?" , "Final word in prayer" , "prayer's ending" , "Last word of prayer" .)