Die down? Some wretched wind lessens (7)
I believe the answer is:
dwindle
'die down?' is the definition.
'some wretched wind lessens' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'DWINDLE' can be found hidden inside 'wretched wind lessens'.
(Other definitions for dwindle that I've seen before include "Grow smaller, taper off" , "Flag" , "Peter out" , "Diminish gradually" , "Grow less - waste away" .)