Cigarette butt from corpse keeps me over a barrel, identifying a variety of contacts (3-9)

'a variety of contacts' is the definition.
(type of contact lense)

'cigarette butt from corpse keeps me over a barrel' is the wordplay.
I cannot quite understand how this works, but
'cigarette' could be 'gasper' (slang term for a cigarette) and 'gasper' is found in the answer.
'from' could be 'e' (I've seen this in other clues) and 'e' is present in the answer.
'a' is present in the answer.
'barrel' could be 'bl' (abbreviation) and 'bl' is located in the answer.
'me' is within the answer.
This accounts for all the letters.
This explanation may well be incorrect...

'identifying' acts as a link.