Marine expert travelling to cooling sea (12)
I believe the answer is:
oceanologist
'marine expert' is the definition.
'oceanologist' can be an answer for 'expert' (I have seen 'Main expert' mean 'oceanologist' so perhaps 'expert' could also mean 'oceanologist'). I'm not sure about the 'marine' bit.
'travelling to cooling sea' is the wordplay.
'travelling' is an anagram indicator.
'to'+'cooling'+'sea'='tocoolingsea'
'tocoolingsea' with letters rearranged gives 'OCEANOLOGIST'.
Can you help me to learn more?
(Other definitions for oceanologist that I've seen before include "Sea scientist" , "Main expert" .)