Get away on Tuesday, fast! (5)
I believe the answer is:
fleet
'fast' is the definition.
(similar in meaning)
'get away on tuesday' is the wordplay.
'get away' becomes 'flee' (I am not sure about this - if you are sure you should believe this answer much more).
'on' means one lot of letters go next to another.
'tuesday' becomes 't'.
'flee'+'t'='FLEET'
Can you help me to learn more?
(Other definitions for fleet that I've seen before include "Street of the hack" , "Swift; group of ships" , "Body of ships" , "Fast as a naval unit" , "Naval force or collection of buses" .)