Fed up of going by boat? (7)
I believe the answer is:
seasick
'fed up' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'of going by boat?' is the wordplay.
'of going' becomes 'sick' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'by' means one lot of letters go next to another.
'boat?' becomes 'sea' (sea boat is a kind of boat).
'sick' put after 'sea' is 'SEASICK'.
Can you help me to learn more?
(Other definitions for seasick that I've seen before include "Nauseous from the rolling of a ship" , "Suffering from mal-de-mer" , "Nauseous on the briny" , "Affected by motion of ship" , "Suffering from mal de mer" .)