Attempt to support friend that's miserable (6)
I believe the answer is:
paltry
'miserable' is the definition.
('paltry' can be a synonym of 'miserable')
'attempt to support friend' is the wordplay.
'attempt' becomes 'try' (I've seen this before).
'to support' says to put letters next to each other (in a down clue, some letters hold others up).
'friend' becomes 'pal' (pal is a kind of friend).
'try' after 'pal' is 'PALTRY'.
'that's' is the link.
(Other definitions for paltry that I've seen before include "Meagre; petty, trivial" , "Meagre, mean" , "Feeble" , "Mean, petty" , "Petty - trifling" .)