Silicone boulder not quite firm under hot, dusty wind (7)
I believe the answer is:
sirocco
'hot dusty wind' is the definition.
(I've seen this before)
'silicone boulder not quite firm under' is the wordplay.
'silicone' becomes 'si' (I can't explain this - if you can you should believe this answer much more).
'boulder' becomes 'rock' (I've seen this before).
'not quite' means to remove the last letter (most but not all of the word).
'firm' becomes 'co' (abbreviation for company).
'under' says to put letters next to each other (in a down clue, some letters go below others).
'rock' with its last letter removed is 'roc'.
'si'+'roc'+'co'='SIROCCO'
Can you help me to learn more?
(Other definitions for sirocco that I've seen before include "Hot Saharan wind blowing into the Mediterranean" , "Hot wind that reaches Italy from Africa" , "Wind from the desert" , "Hot wind reaching Italy from Africa" , "Hot, dry wind from northern Africa" .)