Subject to price fluctuations, some illicit sales see an upturn (7)
I believe the answer is:
elastic
'subject to price fluctuations' is the definition.
I can't tell whether this definition defines the answer.
'some illicit sales see an upturn' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'see an upturn' shows that the letters should be reversed in order (in a down clue, letters go up).
'citsale' can be found hidden inside 'illicit sales'.
'citsale' reversed gives 'ELASTIC'.
Can you help me to learn more?
(Other definitions for elastic that I've seen before include "Flexible (material)" , "Cats lie (anag.)" , "Narrow strip of rubber" , "Able to give a bit" , "Stretcher" .)