New line sure to involve black spray (9)
I believe the answer is:
nebuliser
'spray' is the definition.
(I've seen this before)
'new line sure to involve black' is the wordplay.
'new' indicates anagramming the letters.
'to involve' indicates putting letters inside.
'black' becomes 'b' (as in pencil classifications).
'line'+'sure'='linesure'
'linesure' anagrammed gives 'neuliser'.
'neuliser' placed around 'b' is 'NEBULISER'.
(Other definitions for nebuliser that I've seen before include "dispensed by this" , "Spray - blue rinse (anag)" , "Device for producing a fine spray, for inhaling a medicinal drug, say" , "Used to inhale the drug" , "Drug delivery system" .)