Guide occasionally wangles cheapest class (8)
I believe the answer is:
steerage
'cheapest class' is the definition.
(cheapest accommodation on a boat)
'guide occasionally wangles' is the wordplay.
'guide' becomes 'steer' (synonyms).
'occasionally' indicates alternate letters.
The alternate letters of 'wangles' are 'age'.
'steer'+'age'='STEERAGE'
(Other definitions for steerage that I've seen before include "It's the cheapest way to go by sea" , "Cheap seats" , "Old word for cheapest passenger accommodation in ship" , "Ship's accommodation with lowest fares" , "Course" .)