Something to eat right on the jetty (4)
I believe the answer is:
pier
'the jetty' is the definition.
(I've seen this in another clue)
'something to eat right on' is the wordplay.
'something to eat' becomes 'pie' (pie is a kind of food).
'right' becomes 'r' (common abbreviation).
'on' means one lot of letters go next to another.
'pie'+'r'='PIER'
(Other definitions for pier that I've seen before include "Bridge pillar" , "seaside location" , "'Dock, wharf (4)'" , "Wharf or pillar" , "Seaside platform" .)