Take a holiday? That seems unlikely! (3,4)
I believe the answer is:
get away
'take a holiday? that seems unlikely' is the definition.
'get away' can be an answer for 'take a holiday?' (I've seen this before). I'm not certain of the rest of the definition.
'take a holiday?' is the wordplay.
'take' becomes 'get' (synonyms).
'a holiday?' becomes 'away' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'get'+'away'='GET-AWAY'
Can you help me to learn more?
(Other definitions for get away that I've seen before include "Escape; come off it!" , "Escape; short holiday" , "The car that provides escape for criminal" , "take a holiday" , "Never" .)