Spanish come again? On vacation start adventure (5)
I believe the answer is:
quest
'start adventure' is the definition.
'quest' can be an answer for 'adventure' (thesaurus). I am unsure of the 'start' bit.
'spanish come again? on vacation' is the wordplay.
'spanish' becomes 'que' (I can't explain this - if you can you should give a lot more credence to this answer).
'come again?' becomes 'saywhat' (I've seen this in another clue).
'on vacation' says to hollow out the word (remove centre letters) (after the inside letters have vacated the word).
'saywhat' with its middle removed is 'st'.
'que'+'st'='QUEST'
Can you help me to learn more?
(Other definitions for quest that I've seen before include "Pursuit" , "Hunt, goal" , "Mission" , "Long or arduous search" , "A search or hunt" .)