An infallible adviser could see this as a little round boat! (6)
I believe the answer is:
oracle
'an infallible adviser' is the definition.
(I've seen this in another clue)
'see this as a little round boat' is the wordplay.
I cannot really see how this works, but
'see' could be 'c' (the word for the letter, according to Chambers) and 'c' is found within the answer.
'a' is within the answer.
'little' could be 'l' (abbreviation) and 'l' is found within the answer.
'round' could be 'o' (o is a circular letter) and 'o' is found within the answer.
'boat' could be 'e' and 'e' is present in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'could' is the link.
Can you help me to learn more?
(Other definitions for oracle that I've seen before include "Diviner of the future" , "Wise utterance" , "Augur - prediction" , "Fount of divine inspiration" , "One believed to give divinely-inspired answers" .)