Fruit put on heap — one concerned next clue but one (8)
I believe the answer is:
limerick
'one concerned next clue but one' is the definition.
I can't tell whether this defines the answer.
'fruit put on heap' is the wordplay.
'fruit' becomes 'lime' (lime is a kind of fruit).
'put on' is a charade indicator (letters next to each other).
'heap' becomes 'rick' (rick is a kind of heap).
'lime'+'rick'='LIMERICK'
(Other definitions for limerick that I've seen before include "Humorous five-line verse" , "Humorous poem of 5 lines, and Irish county" , "Witty poem from mid-western Irish city" , "Type of humorous verse" , "Rhyme" .)