Yes, tourism may be puzzling (10)
I believe the answer is:
mysterious
'puzzling' is the definition.
(thesaurus)
'yes tourism may be' is the wordplay.
'may be' indicates an anagram.
'yes'+'tourism'='yestourism'
'yestourism' with letters rearranged gives 'MYSTERIOUS'.
(Other definitions for mysterious that I've seen before include "Secret" , "Enigmatic, baffling" , "creating a puzzle" , "Spooky" , "Cryptic - baffling" .)