Mournful bloke weighed down by scheme (8)
I believe the answer is:
plangent
'mournful' is the definition.
(plangent can mean sounding mournful)
'bloke weighed down by scheme' is the wordplay.
'bloke' becomes 'gent' (I've seen this before).
'weighed down by' says to put letters next to each other (in a down clue, some letters go on top of others).
'scheme' becomes 'plan' (synonyms).
'gent' after 'plan' is 'PLANGENT'.
(Other definitions for plangent that I've seen before include "Resounding" , "Pathetic" , "booming" , "(Of sound) mournfully resonant" , "Mournful-sounding" .)