Armada almost making escape (4)
I believe the answer is:
flee
'escape' is the definition.
(I know that escape has the is a more specific form of the action flee)
'armada almost' is the wordplay.
'armada' becomes 'fleet' (fleet of ships).
'almost' means to remove the last letter (most of the word but not all of it).
'fleet' with its final letter taken away is 'FLEE'.
'making' acts as a link.
(Other definitions for flee that I've seen before include "Abscond" , "Leave" , "Take flight" , "Do a runner" , "Turn tail" .)